It means, on the...
Grilling... INDIRECT HEAT ONLY, if you put the meat directly above the flame, it will cook it too fast and make it tough. Put the meat on the top shelf and give it some time.
If you have a single level grill, then put the gas/coals on one side and the meat on the other side.
Ex.: Sausages - top shelf, if too hot for the sausages, the casing will pop and the outside will be done/over done and the inside raw. 15-20 minutes
Steak - Indirect on same or top level, to medium rare/medium. If you cook more than medium, keep a watchful eye, it could end up tough and is not recommended.