The word well has several meanings:

1. To do something in a good or skillful way. When you play soccer well, you control the ball smoothly and make smart passes. When you write well, your sentences are clear and your ideas connect logically. Well describes quality: how thoroughly, skillfully, or successfully you do something.
2. To be healthy or in good condition. When someone asks “How are you?” and you answer “I'm well,” you mean you feel healthy and things are going fine. A doctor might say a patient is doing well after surgery, meaning they're recovering as expected.
3. A deep hole dug into the ground to reach water. For thousands of years, people have dug wells to access underground water for drinking, cooking, and watering crops. In fairy tales, characters often make wishes by tossing coins into wishing wells. Some wells go hundreds of feet deep to reach clean water.
4. Used to start a sentence when you're thinking or transitioning to a new thought. “Well, I hadn't thought of it that way” or “Well, what should we do now?” This use of well gives you a moment to gather your thoughts before speaking.

The phrase well-being combines the first two meanings, referring to someone's overall health and happiness.