Ai Weiwei's art is really interesting. I like his style, use of materials, and the level of abstraction in his pieces.
I'm not familiar with Ai Weiwei, is he an artist? 
He is an artist.
What type of art does he produce? 
He produces abstract and contemporary art. You can google his art and see some examples.
Interesting, I don't know a lot about abstract art, it sounds interesting. 
Yeah, it is really interesting. I like abstract art because it doesn't have a clear, surface-level meaning, and that forces you to think more deeply than you otherwise would have.
Who is your favorite abstract artist? 
That's a difficult question, since I'm partial to the style of the art more than the artist. I will say, though, that Ai Weiwei is easily a top 5 pick.
I tend to like Picasso, I think that is the best type of art.