"What are your doubts?"
Translation:Jakie są twoje wątpliwości?
"Wątpliwość" is when you are not sure about some facts. "Zwątpienie" is when you lose faith in something or someone.
You may have "wątpliwości" when you're not sure about something, e.g. when you don't know if your decision is going to be good, if your plan is going to work, if someone will like you etc.
"Zwątpienia", on the other hand, are kind of second thoughts, when you suddenly stop believing that something makes sense or you start to doubt in your success and (sometimes) despair. This word, however, is used very rarely, you'd rather use the verb "zwątpić (w coś)". For example:
Zwątpiłem. - I gave up./I let go./I stopped believing [in the point of doing something].
Zwątpiłem we wszystko. - Nothing makes sense to me anymore. (hard to translate literally)
Mam wątpliwości co do twojego planu. - I have doubts about your plan. (=I'm not sure it'll work)