So let's say you have a piece of clay. You can push or pull it from different directions, right? This makes the clay stretch or bend or break.
Now, imagine if the clay was actually a big rock and it's been there for millions of years. But you can't see how it got all those cracks and bends in it just by looking at it. That's where paleostress inversion comes in.
Scientists use really fancy equipment and math to figure out what kind of forces acted on the rock in the past. They look at things like the shape of the cracks and the angles of the bends to figure out which direction the rock was pushed or pulled.
It's like being a detective and looking at clues from the past to solve a mystery. Except the clues are in rocks and the mystery is millions of years old!