Need Help, I do not understand this backlink method

Hello friends
I want to ask you something to you I see my competitor take backlinks from these kind of sites
http://www.sarakin7.info/
but when i spy on them and try to get the same backlink i never see a way to do that. There is no contact button or something like that also when i check with link assistant to send them maybe a guest post req. there is no email they provided. I dont think this is a PBN because there is a lot of links. Is there anybody who can help me about this ?

Its Paid links. I saw it on sale somewhere in bulk along with other sites cheap, but i skipped as the guy posted all link in public on his thread

Ah i see thank you very much

Your competitor bought some link from these type of site