What is when a guy asks what are you doing tonight?

When a guy asks "what are you doing tonight?" it could mean different things depending on the context of the conversation. Generally, it could mean that the guy is interested in spending time with you and wants to make plans to hang out. It could also indicate that he wants to know your schedule and availability for future plans.

If you are interested in the guy and want to spend time with him, you can respond by letting him know your availability and suggest some activities that you both can do together. However, if you are not interested in him or have other plans, it is okay to politely decline his invitation and let him know that you are busy or have other commitments.