Kebap (or kebab) simply means "roasted," and usually refers to roasted meat in some form. "Kebab" is a category of food which is typically Turkish dating back to the time when the nomadic Turks learned to grill and roast meat over camp fires.
The most familiar Turkish kebap is Doner Kebap which is made by stacking layers of sliced leg of lamb on a large upright skewer, which is slowly rotated in front of a vertical grill. As the outher layer of the meat is roasted, thin slices are shaved off and served.