National Treasure in South Korea is like a very special toy or a treasure that the whole country loves and takes care of. This special toy or treasure is usually a really old and important building, statue, painting, or artifact that shows their country's history, culture, and way of life.
Just like how you take care of your special toy or treasure, the whole country of South Korea takes care of their National Treasures. They protect them so they can last a very long time and keep them clean so they look nice and pretty.
People in South Korea also like to share their National Treasures with others. They want people from all over the world to see them and learn about their history and culture.
So, whenever you visit South Korea, you can go see all of their National Treasures and learn a lot about what makes their country special and unique.