What is when a guy says you mean the world to me?

When a guy says "you mean the world to me," it essentially means that you are incredibly important to him. He may see you as his top priority, someone he deeply cares for and loves. It is a very strong and emotional expression of affection and can be a significant milestone in a relationship. It may also mean that he is willing to do anything to keep you happy and satisfied. Overall, when a guy says this, it signifies a deep connection and devotion towards you.