How to make a Russian-English site for the sale of cats in terms of SEO?

Question

Search Engine Optimization

Good afternoon. I’ll make a reservation right away that I don’t know anything about search engine optimization, practically.
I have a site for the sale of cats and their descriptions with Russian and English content. Advise how best to do it, I think the options are as follows:
1. subdomains ru.site.com and en.site.com, depending on the subdomain - content is loaded in Russian or English. But what impact will this have on SEO, will it count as two different sites, or one? And if different, will site.com come third? And what to show on site.com, in the sense of what language, to somehow determine it yourself, depending on what?
2. site.com/ru/ and site.com/en/ respectively, by default it is also not clear where to transfer, to /ru or /en
3. maybe there are some other options that are better than those that I suggested?
Well, yes, I want search engines to properly index both options, both Russian and English, and these two options do not interfere with each other's normal functioning. That is, if a user types my keywords in Russian, he will be taken to the Russian version, if, for example, in English, then to English, and so that these versions do not harm each other from the point of view of search engine optimization.

Answer 1

We recommend that you choose the first option, but host the main language on the main domain, and additional languages ​​on subdomains. More about this how to make multiple languages ​​on the site