Translation:Do you have pretty T-shirts for the concert?
Why can't bonitas mean beautiful? This is the first time I have seen "cute" used in Duo????
Bonitas does mean beautiful, but unlike in English, it can also mean pretty. "Cute" in this context also means pretty, and so bonitas can work for it.
T-shirts son camisetas; shirts son camisas. No es posible escribir shirt aquí.
Earlier in this level it accepts tops for camisetas! but not in this case for some reason. It gives vest as a correct example - whoever would say do you have pretty vests???? And in this post it is saying T-shirts - at least that's ok.
When do you use "tú" and "tu"? Sometimes there is an accent, sometimes not.