I'm learning English on my own by reading books and watching movies, but when it comes
to speaking or writing, I never now what word I must choose at the right moment.
I catch myself on putting russian equivalent but it is far not always work.
Furthermore many things could be expressed in English by a few words, at the same time
in Russian you would be need maybe a couple of sentences to express the same thing.
Very often I think it's impossible to translate equally.
It looks like you are doing really well! You said :
"I'm learning English in my own by reading books and watching movies, but when it comes to speaking and writing, I never know what word I must choose at the right moment. I catch myself on putting the Russian equivalent but it doesn't always work."
From language to language it is generally very strange to directly translate, and often times is grammatically incorrect. There are many languages where there are no equivalent phrases or words to translate into.