The phrase "___ kicks ass!" means that something is really great. You use it like this:

Have you played Call Of Fury 3 yet? It kicks ass!

This phrase is very casual. It's used more by younger people and less by older people.

You use "___ kicks ass" to talk about things that are great in a kind of aggressive way. So use it when talking about things like

• video games
• cars
• sports teams
• technology

It would be a little unusual to tell someone that, for example, their flower garden "kicks ass".