Kalevipoeg is a very famous Estonian mythical hero, kind of like a superhero in old stories. He was very big and strong, and he had many adventures where he fought monsters and saved people.
Think of it like a really cool cartoon or comic book where there's this amazing character who can do all kinds of impossible things.
People in Estonia have been telling stories about Kalevipoeg for a long time, and he is a big part of their culture and history. In fact, some people even believe he was a real person who lived a long time ago!
Overall, Kalevipoeg is a really cool and interesting character that people in Estonia love to talk about and learn more about. He is definitely a hero worth getting excited about!