The WA will take over your world map and overlay the portal numbers. Use custom options to set your portal number and if your raid uses different portal numbers you can shift the numbers with the second slider.
Many auras put portal numbers on the minimap, but this is the only way to show your actual location in relation to the portals.
Note: This aura disables your world map, so you will need to reload UI in order to return map functions after the fight