The $xy$-coordinate Plane is a two-dimensional surface defined by two perpendicular axes. The $x$-axis runs horizontally and the $y$-axis runs vertically. If you're wondering what is meant by "two dimensional," think of the number line we studied in arithmetic. That is one-dimensional because it only runs from the left to the right. The $xy$-coordinate plane is two-dimensional because it not only runs from right to left but down to up as well.

The two axes intersect at a point called the origin, designated by the coordinates $(0,0)$.

A point is represented on the $xy$-coordinate plane by a pair of numbers, written as $(x,y)$. The $x$ coordinate refers to the position on the $x$-axis (the run that ones horizontally) and the $y$ coordinate refers to the position on the $y$-axis (the run that runs vertically). For example, the point $(-2, 3)$ means we first move two points to the left and then three points up.

What's the point of it?

Good question! Think of coordinate geometry in general and the $xy$-coordinate plane specifically as a "bridge" that connects algebra to geometry. You can represent algebraic equations and inequalities in "graphical" form on the $xy$-coordinate plane.