I bought this game from steam and founded that internal name is Fallout New Vegas (RU)

1. What is mean?
2. What resriction I have? (play in foreign countries etc)
3. I live in Ukraine (UA) why I have Fallout New Vegas (RU)
4. Can I buy via steam full version non-RU?

Steam automatically checks your IP and downloads the version appropriate to your country. I live in Germany, so whether I like it or not, I get the German version.
Either Steam has it set up so that Ukraine recieves the russian language version or you were using an IP address that gave Steam the idea that you were russian (sometimes my IP makes websites treat me as if I were Dutch). Sorry I don't know.
Since each country censors the game to a different extent, it's unlikely you can get the game in english if the Ukraine chose to add additional censorship at all.

I'm guessing they don't have a Ukrainian version, so you got a Russian one. Offensive as it is for a chochol to play a version of the game designed for a moskal

P.S. Oh, am I glad they didn't do a Hebrew version! I much prefer the original language in books, movies and games alike- when I know that language, that is.