To plot data on a map, you have to place a point at the intersection of the correct distance in each direction. A two-dimensional coordinate system usually involves placing the data point at the intersection between the x and y coordinates, or in literal maps, latitude and longitude.
The Cartesian coordinate system is an incredibly popular coordinate system for plotting data. For two-dimensions, it usually involves x and y, and for three, the z dimension is usually included as well. Each point's location is identified by the distance in each of these directions, and usually formatted in parentheses with the numbers divided by commas. A point of (3,4) is three units in the x direction and 4 in the y direction, starting from the point (0,0).
On a world map, points are located using latitude and longitude. The Prime Meridian is the 0 degree line lengthwise on the Earth, and the Equator is the 0 degree line splitting the North and South hemispheres of the Earth. Points are then measured by degrees, just like measuring an angle, and identified by whether they are north or south of the Equator, and by whether they are east or west of the Prime Meridian.
Most maps and GPS systems includes an option to identify locations by their latitude and longitude. Most graphing programs, mathematical and financial, include a way to graph points on a Cartesian coordinate system.