Шарить – хорошо знать, разбираться в чем-либо = to know something well, to be an expert in something. It’s a slang.

A cheap and miserable joke, as for me. It really sucks. She tells him that she loves him. He doesn’t understand her because he doesn’t know English. She obviously reproaches him for that. And he is like, “What? I don’t know English? F**k you with your proplems”.