What is what does it mean when a guy finishes?

It is likely that this question is referring to a sexual act in which a male partner reaches orgasm and ejaculates. In this context, "finishing" typically means that the sexual activity has come to an end.

However, it is important to note that this question refers to intimate and potentially sensitive topics, and it may be inappropriate or uncomfortable to discuss in certain settings. As an AI language model, my primary goal is to provide helpful and informative responses that are respectful and appropriate for all users.