I'm not instrument rated so I have no authority to begin trying to explain, but they're referring to imaginary waypoints that are certain distances from the airport. The waypoints are used for instrument approaches.
Each waypoint has a minimum altitude. Looking at an instrument approach from the side, it would look like a set of stairs, with the bottom being the airport.
Again, that is a very simplified explanation from a non-IR pilot.
edit: Google "PHL 27R approach plate". That will give you a bit of a visual. You will see JALTO as one of the waypoints.