Teaching in English is still not widespread in Russia, so most universities will teach you in Russian. In most cases, they organize one-year preparatory language courses for foreigners, and the people who have completed these courses are believed to have sufficiently mastered Russian to attend classes. However, judging from my personal experience, I find that one year is absolutely insufficient to master Russian to a proper degree. Therefore, you need to be prepared to work hard. If you do, you will compensate the drawbacks of our educational programmes by your own hard work. If you are not prepared for hard work... maybe it is worth to reconsider your choice of a place to study. I mean, it is not impossible to receive good education in Russia -- quite the contrary. But in most cases, it is a very difficult thing to do for a foreigner.