To dine means to eat a meal, especially a special or formal one. It can also mean to have something, like time or attention.
When we think about eating out with friends or family, "dine" usually comes up. Imagine going to that fancy new restaurant you've been wanting to try - the waiter says "Shall I make a reservation for you to dine at 8?" Here, "dine" means eat a meal in a place where people often go to enjoy food. But we also use "dine" when talking about eating in general - like saying "I'll have time to dine with you later this week." In this case, "dine" just means have some free time to eat whatever you want.
To eat; to eat dinner or supper.
