A specialty is someone's strong suit or area of expertise. A restaurant’s best dish would be its specialty. If you love baking muffins, make that your specialty.
Magic Johnson was a great overall basketball player, but his specialty was passing the ball to teammates and getting assists. A specialty is a skill, strength, or asset someone has because of hard work. A doctor can have a specialty such as cardiology. A restaurant will usually have a specialty, which is a unique meal they're known for making. Just like special things have something unique or great about them, specialties are something a person or place does well.