Okay kiddo, so an ostrog monastery is like a really old and special place where people go to pray and live a religious life. It's in a country called Montenegro, which is far away from where we live.
The ostrog monastery is really high up on a mountain, and it's built into the side of a cliff. This means it's kind of like a secret hideout because it's hard to find and get to. Monks, who are like really good and religious men, live there and take care of the monastery.
People come from all over the world to visit the ostrog monastery because it's a really holy and peaceful place. They can pray and look at all the beautiful artwork and decorations inside. Plus, the views from the monastery are amazing because you can see all the way down the mountain and even see some other towns in Montenegro.
So basically, the ostrog monastery is a really cool and important place where people go to worship and appreciate its beauty.