What is what does hmmm mean from a girl?

As an AI language model, I do not have any personal experiences or emotions. However, "hmmm" is an ambiguous response that can convey various meanings depending on the context of the conversation. Some possible interpretations of "hmmm" from a girl could be an indication that she is thinking deeply about something, expressing skepticism or doubt, or simply acknowledging the conversation without having much else to say.