The prime meridian and the equator on a map represent the y-axis and x-axis on a coordinate plane. Specifically, the prime meridian is the y-axis and the equator is the x-axis. You use the prime meridian and the equator to locate places by their distances from these two reference lines. Using longitude and latitude (0,0), you can locate places on a map and it’s called the y-axis and the x-axis on the coordinate plane.