It's actually quite understandable. You regard a piece of paper as a complete set, draw a circle on it, it is a set, and the part outside the circle is the complement of this set. Drawing a point on paper is an element, drawing a point in a circle belongs to this set, and drawing it outside the circle does not belong (also belongs to the circle). The concepts of intersection and union are also understood in the same way.

The combination of numbers and shapes is a very important method in high school mathematics. If you master it, you will master the college entrance examination to some extent! Come on, I believe you can understand!