Yes, in fact, the coordinate system to be studied in the future has four quadrants (that is, four areas are separated by a cross), so all x y are positive and negative. For example, the upper right is all positive, the upper left is X negative Y positive, the lower left is all negative, and the lower right is X positive Y negative.

So the coordinates can be positive or negative. But as you said, it represents four points. (2,3)(-2,3)(2,-3)(-2,-3)