[Question] Would using 2 languages on 1 site be bad for my site?

Hi everyone, I don't have many posts but I read here all the time and the amount of stuff I learned is awesome. I don't see how my idea could be good for my site but I decided to ask some fellow Internet Marketers for their opinion anyways. Long story short, I speak english and french, and I just found some very good French keywords in the same niche as one of my English microniche sites. I was wondering if having some french content on my english site would be bad for my SEO? I also thought of using an option that allows the reader to pick either french or english and the content would then switch. The french keywords don't mean the exact same thing as the english ones but I can easily write a text that means the same around them. The problem would be that I would have french content with an english domain name, but the keywords I found have almost no competition so I can definitely rank them anyways. I don't want to build another French site right now because this niche isn't earning me a lot.

Thanks a lot for your help, you are more than welcome to contribute your opinions and ideas.

Yes if you are going to do it, make sure the reader has the option to switch between languages or have it based off of countries ip address. It really depends I have ranked my sites for English keywords in other countries even. So im sure it would help by having multiple languages. The more content the better. Domain name will not matter that much to English or French speakers.

I was wondering about this as well. I am planning to create a website for a digital marketing company in English and Russian. Any input on how to do this effectively without hurting SEO?

I am not really sure about this but IMO it won't be good for your website. You might face some difficulties with Google. But as I said, I am not very sure about this. Good luck (y)

Quick question... I am also interested in building a multilingual site and wondering which CMS you use?