Question

what are coordinate planes

Answer 1

http://www.math.com/school/subject2/lessons/S2U4L1GL.html#
It is formed by a horizontal number line, called the x-axis, and a vertical number line, called the y-axis. The two axes intersect at a point called the origin.
You can locate any point on the coordinate plane by an ordered pair of numbers (x,y), called the coordinates.