A duke is like a very important leader in a big castle. Imagine a king or queen who rules over a whole kingdom. Now, the duke is someone who helps them by taking care of a smaller part of that kingdom, like a special helper who makes sure everything is going well in their area. Think of it like a captain of a team, making sure everyone is doing their job and everything is running smoothly.

Another way to think about a duke is like a big brother or big sister who helps take care of the family when the parents are busy. The duke makes sure the people in his area have what they need and that everyone is safe and happy. He has a lot of responsibility but also gets to make important decisions.

Picture a duke as someone who has a special badge or crown that shows they are important and have a special job. They might wear fancy clothes and live in a big house or castle, but their main job is to help the king or queen and the people around them.