Schtick*. I think one synonym could be persona, or character. She is saying that she isn't going to play the Nice Girl persona, stereotype, or character that many may perceive her as. Can also refer to comedic characters, or bits, in some contexts. I hope this makes some sense. Sorry, I don't know any Russian. Let me know if you have any questions!

I looked this up because I had never heard of her - lol - but it's actually "Nice chick schtick ain't happenin'" - Schtick is a yiddish-derived word for the style of one person or the way they perform or do something. Probably she is saying that the "nice chick schtick" - the nice girl routine - isn't going to happen anymore. I hope that helps! Sarah