Is there a function on telegram that translates Russian?
No, but you can copy the text, and translate it using Google.
Only takes a couple of keystrokes.
There are two things I am aware of (but, I am not a techie.)
The first one is that on google at least when you are on a foreign language page it usually offers you an opportunity to switch to whatever you choose. If that doesn’t come up (and sometimes it doesn’t) there is a small icon with two little different colored squares located next to the star that you use to bookmark. Those little stars will bring up the option to select language translation.
The other possibility but only available if whoever posted the item entered it is if you right hand click your mouse an option may come up offering “google lens” If you click on that it will allow you to have the page translated at the side and you can read it there.
Maybe other more technically advanced freepers than me (which means everybody...:-) can suggest other ways.