Okay kiddo, so in Transylvania there are some villages where the people built their churches in a special way. They made the walls really thick and strong, and they put towers and walls all around the church too.
Do you know why they did this? It's because a long time ago, the people who lived in those villages were afraid of being attacked by bad guys called invaders. So they needed a strong place to stay safe.
The fortified church was like a big fortress or castle where the people could hide inside and be protected from the invaders. That's why they built walls all around it and big doors and windows that could be closed tightly.
The church was also a very important place for the people to pray and worship, so they wanted to make sure it would be safe from any harm. These fortified churches are still standing today and you can visit them to see how clever and strong the people of Transylvania were to protect themselves and their faith.