you (in a question form): it is equivalent to "you?", if it's used as a single sentence question alone, or if it marked the end of a question.

you (in a question form); you :

you: "呢" serves as a modal particle. Mostly followed by a short pause or a comma before the rest of the sentence.

how about you?; what about you?; you?; and you?; this…of yours [colloquial]