Dude Listen, you don't need to go through the bins for food.
Firstly, I've been in the same situation years ago, and learned eventually about how to do this shit properly. Now you're in spain, so you have as much free food as you can shake a stick at. Ask people where the local Caritas is, they'll have free meals (like, better meals than I usually eat when working full time and/or have tons of cash) and in any larger city in the country there will be a mixture of different services like this meaning that you can (should you wish) eat five full meals a day easily for free.
You can also sleep in the Caritas and in various other centers (although you're right to be careful with the laptop, you're carrying around more wealth than every single person in the entire place combined and then some with that laptop, some will be tempted).
If you don't know where it is, you obviously have access to google maps so find it that way, search for Caritas (city name) and you're good. You can also ask people "¿Donde esta el Caritas? Por Favor" (Where is the Caritas please), to which they'll reply lots of stuff that I'm sure you can't understand right now but they'll also point and gesticulate, so thank them and keep moving in the direction they pointed too etc... Well so much for Firstly...
Secondly, if you're unwilling to do it yourself (take food from bins), you should absolutely NOT be willing to allow that weakness (that's exactly what it is, trust me I've been there, I know what I'm talking about) to make you take food away from those other people who actually are strong enough to have pushed through their pride like that and have the pitiful amount of food that they have to show for it. That's NOT OKAY. Those people have literally NOTHING, stop taking from them and act like a fucking man and get your own damn food. You have hands just the same as they do, grow up and use them instead of expecting them to do it for you.
When I was in your position it took me five solid days of eating nothing while lugging a 15kg backpack around all day long (if you don't know, you need about three to four times the normal calorie intake to do that normally if you're covering 20 miles a day) before I managed to make myself hit up the bins. I was in Spain too, and also didn't speak the language at the time and after five days of lugging that pack with no food at all, I realised that my body was starting the process of dying.
It's a subtle feeling, not really physical, I mean sure there are physical things, my legs didn't work properly at all (damage from hiking with a pack and no food for a total of probably 120 miles or so over those five days), I was utterly lethargic and by that point I couldn't hike anymore because walking 500 meters would require stopping 4 times and waiting 10 to 15 minutes until my blood sugar levels re-balanced before continuing. But the feeling that my body was literally dying wasn't like that, just some increasingly forceful yet quiet certainty that my body was telling me that it was at the end of what it could do and that there wasn't going to be anything more than this unless something changed.
That was the day that I took food from the bins. I understand that you find the idea impossible, trust me I get it. It took THAT to make me do it ffs. It took THAT to make me realise that if I died right there, then I was literally dying for pride. I'd be dying for no better reason than that I wasn't strong enough to master my pride in my self image as somebody who wouldn't stoop so low as to eat from a bin. Fuck that for a reason to die, that's a goddamn shitty, stupid and downright pathetic reason to let yourself die is what I decided, and that got me past my inability to do it.
So what I'm saying is that I get it, you don't want to go into the bins, but understand that every person around you that DOES go into the bins, has managed to push through their pride like that, and it was every bit as hard for them as it is for you now, but they did it. And they DID NOT go through that just so they could give food to somebody like you that isn't willing to do the same. It took me almost 8 hours a fucking day to find enough food to survive (not really live, just survive) and no way in hell would it have been ok for somebody to ask me for a load of that food just because they didn't want to use their own fucking hands to pick up food that's right in front of them because they're too proud to do it, fuck that.
You need to fucking master yourself if you're going to sort your life out from the place where it is right now, regardless of the food situation. You're homeless, you have no income at all, you're in a country where there is literally ZERO chance of getting a job even if you DID speak the language because the economy of Spain is destroyed. You will not get a job in that country, not within the next two years at least, and your chances honestly wouldn't be much better if you were spanish and could speak the language, it's THAT bad over there right now so forget that. If you want a job then leave the country ASAP because it's not an option right now where you are.
If you're getting at least SOME money from somewhere then FFS DO NOT FUCKING WASTE IT ON A ROOM! What the hell are you thinking?! You're not going to die by sleeping outside! Money will be the single hardest thing in your life right now, it has to be spent only on things that are absolutely NECESSARY. You can sleep for free, you CANNOT take a train to France, or a ferry to Britain for free! Prioritise the money on thing WHICH CAN ONLY BE DONE WITH MONEY. Not just crap like "It'll feel nice to sleep in a bed". Who the fuck cares if it'll feel nice to sleep in a goddamn bed? It doesn't MATTER whether or not it feels nice.
Understand this, and understand it well, I'm going to pull zero punches here: If you don't change your life and bring it back under your control to at lest some degree by mastering yourself with regards to the above stuff, within two years there's an extremely high possibility that you will be dead. I met a bunch of great people on the streets, honestly a good few of them are dead now, it sucks but it's the truth. Out of all the people I know who had a really bad time and didn't make it, the defining characteristic was a lack of self mastery and an unwillingness to get the fuck out of their comfort zones.
Sorry if this sounds like a rant but I really think it could help you to hear it.