What is he stood me up but apologized?

If someone "stood you up" it means they didn't show up for a planned meeting or date without any notice or explanation. However, if they apologize, it means they acknowledge their mistake and are sorry for not showing up. Depending on the circumstances and the relationship, you may choose to forgive them and give them another chance, or you may decide to move on from the situation. It's important to communicate your feelings and expectations to prevent similar issues from happening in the future.