Informally you could call it "Beach brolly" (BEnglish)

As I didn't had situation in whitch I would need to know that word as much..I would probably just say sun umbrella. As I read here I know its not best way to say it tought.

You can see some of the other responses for synonyms. If you're asking because you're worried beach umbrella doesn't sound natural, though, it does.:)

am not a native speaker but i would say:-sun cover

I would say, "parasol" is a term sometimes used. Also, "sunshade", but that's not quite an umbrella.