Mia, I agree with everyone else that شُو بِتْسَوِّي means: "what are you doing?"

Yet, with a tiny change it could mean something completely different :)

Like in شو بْتِسْوَى, which means how much it worth? or how much this costs?

of course both are only used in spoken accents -especially Levant- and they

are not from MSA.

or "what are you doing?"

that means "what do you do?" and it isn't in classical arabic (just in a dialect)