Okay kiddo, so have you ever seen a hill or a small mountain? Amba is a word that people in some parts of the world use to describe those types of landforms.
When the Earth was formed, there were a lot of different forces that helped create all the mountains and hills that we see today. Over time, rocks and dirt were pushed up by these forces, creating big high points in the ground.
Sometimes, people build things on top of ambas, like castles or fortresses. This is because they can be a good place to defend from. Plus, they're usually pretty cool to climb up and look out from!
So, that's a basic explanation of what ambas are. They're just another type of landform, like hills, mountains, and valleys.