Translation:Are there wallets?
What he said, but also if you need clarification, consider that は asks whether there are wallets and が asks if they have wallets. You might think they mean the same thing but the specific word choice changes the meaning ever so slightly. That's the same amount of difference here
I'm looking for some good links on this topic myself and can't really find any. This hinative answer is the best thing I've found so far.
My interpretation of their answer:
車がありますか (kuruma ga arimasu ka) means "is there a car?" (a question of existence).
車を持っていますか (kuruma o motte imasu ka?) means "do you have a car?" (a question about your personal ownership).
車はありますか (kuruma wa arimasu ka) basically means "is there a car?" (a question of existence) but is used colloquially to mean "do you have a car?" (a question about your personal ownership).
So according to this answer, it seems like が would make more sense. This is only one native speaker's opinion, so I'm interested to hear if anyone else has found some good links, because duolingo clearly prefers は in questions and there must be some kind of logic behind that.