Most of Ukraine speakers know Russian very well. Very little Russian knows Ukrainian only who are living in Ukraine or near the border or have relatives in Ukraine. This languages are different in spite of the fact the root is common and many words are the same. For example, my mother is Ukrainian. I don’t understand Ukrainian! (( The construction of sentences are the same, most of words differ.

Ukrainians can easily understand Russian language but Russians cannot understand Ukrainian language

I've developed an understanding, that Russian and Ukrainian are somewhat similar like Spanish and Portuguese. I speak Portuguese and I'm able to understand more or less (quite well in fact) Spanish - thought I've never leaned it. But if you speak Spanish, it want be just as easy for you to understand Portuguese. People who speak Ukrainian will rather understand Russian even if they've only heard it a couple of times in their life. On the contrary, if a Russian native speaker didn't hear Ukrainian before, he(she) will probably not understand a bigger part of the message made in Ukrainian (at least at first). + one interesting fact in addition: I once made an experiment with a girl from Poland which didn't know a word neither in Russian nor in Ukrainian before. she spoke Polish and I spoke Ukrainian, for an hour or so. we've just met so it wasn't because we knew each others mind well but we in deed understood every word we said/heard in the language which we never used before. And after that we tried to do the same with Polish and Russian - and she failed to understand the main (most important) part of each sentence.. So Ukrainian and Polish are closer in order to reach understanding - even though historically and linguistically Russian and Ukrainian belong to one language group while Polnish belongs to another. Belorussian and Ukrainian are also quite close so that we can understand each other pretty well (like Polish and Ukrainian). And both these languages historically and linguistically belong to the same language group as Russian. But than again, Russian language speakers do not understand Belorussian as good as Belorussian language speakers understand Russian ;).

Я не знаю ураинского. Могу понять общий смысл без подробностей.

Russian and Ukrainian have common and easily recognizable sounds and overall speech flow and intonation. Yes, there are a bit more common words than, say, between English and Russian, and I mean words like avocado=авокадо. But still not nearly enough for a Russian speaker to understand Ukrainian. Basically, you're lucky if you could pick out one word in a Ukrainian sentence.