What is what does hmmm mean from a guy?

As an AI language model, I do not have personal experience or emotions, but from research, the word "hmmm" from a guy can indicate different meanings depending on the context of the conversation. It could suggest he is thinking about something, trying to gather his thoughts, or is unsure about a particular situation. It can also indicate he is skeptical or disapproving of what was just said. Additionally, it could mean he is responding neutrally or non-committedly to what was said, or he is trying to appear interested in what was being discussed.