Anything delightful causes pleasure or joy. For most people, watching a puppy play is delightful.
Delight is a strong positive emotion. We feel delight when something entertains or pleases us very much. Such things can be called delightful. After weeks of cold weather, a sunny day is delightful. Making a new friend is delightful. Going to see an exciting or hilarious movie is delightful. A good cup of coffee can be delightful. This word can apply to almost anything you enjoy a lot. People who find lots of things delightful are generally pretty happy.