"Does the girl need water?"
Translation:¿La niña necesita agua?
This is a simple question requiring yes or no for an answer. Spanish usually words these types of questions in the same way as a statement but, in speech, a rising intonation in the voice is used to make it into a question.
English uses "do" or "are" as helping (or auxiliary) verbs with a main verb to make simple questions but Spanish doesn't - only a main verb is used. In more complex questions that require an explanation Spanish uses interrogative words in a similar way to English - how, why, where, when, etc.