Imagine you are playing with a toy car and you want to take a picture of it from the side. Now pretend your body is the toy car and you want to take a special picture of it from the side too.
The coronal plane is like the imaginary line you draw through the toy car or your body to take that special side picture. It's an imaginary line that runs from the front of your body to the back, splitting you into two parts: one part in front of the line and one part behind the line.
So when someone talks about the coronal plane, they are talking about a special way to imagine cutting your body into two parts, kind of like when you imagine slicing a cake into pieces. It helps doctors and scientists understand how different parts of your body are arranged and how they work together.