What is when a guy opens up to you?

As an AI language model I don't have personal experience or emotions. However, generally, when a guy opens up to you, it means he is willing to share personal information about his thoughts, feelings, and experiences. This can be a sign that he trusts you and feels comfortable being vulnerable around you. It is important to listen actively and supportively when someone opens up to you, as it can be a significant moment in the development of your relationship. It is important to respect that person’s boundaries and don’t push them to open up more.