General covariant transformations

General covariant transformations are like a set of special rules for how we can change coordinates of a mathematical object (like a circle in space) without changing the shape or size of the object. It's like if you move a circle around a piece of paper, but no matter where you move it, it looks exactly the same. That's what general covariant transformations do - they allow us to move things in a way that keeps their shape the same.