What is when a girl says hmm what does it mean?

The meaning of "hmm" can vary depending on the context and tone in which it is said. It can indicate a lack of interest or attention, confusion, uncertainty, or contemplation. It can also be used as a filler word to express a noncommittal response. Therefore, it's essential to consider the situation and the girl's body language and tone to determine the intended meaning behind "hmm."