When we see a graph on a page we really don't think in terms of dimensions. But the graph above has only two axis or two dimensions. It is a plane.
Watch how the x-y graph rotates you can see it is a plane....
-------------->spin on -------->-
spin off
Point B has the coordinates (2,4). Starting from the origin (0,0) to reach point B we count 2 spaces to the right, then four spaces up.
What are the coordinates of point A?