The Geoposition is a co-ordinate based system. It allows you to tell people where you are and to navigate the rich world of dofus.
It follows the format of (x,y), and the centre of the entire world at (0,0) is a temple in Amakna. Dofus' y-axis is inverted from the standard Cartesian coordinate system; i.e., "up" from (0,0) is (0,-1), "down" from (0,0) is (0,1).
Opening up the Geoposition screen by clicking this button on the right of yout screen in game will give you a map which you can look over, check the position of the nearest thing, zoom and place flags. Placing a flag will allow the compass (below your health display on the main screen) to point to where you plan to go to. Looking on the Geoposition map will also give you guidance through hard to navigate areas, e.g. the labyrinth. Some dungeons (and other areas) override the world map, replacing it with their own.