Kebab means grilled meat in Turkish. Kebab is made of lamb and beef. In the United States, this is usually called gyros meat, while a kebab is a stick with small cubes of any kind of meat or fowl and vegetables that is roasted on a grill.
There are different variants of kebab:
European:
Enterprising take-away operators (catering generally to drunken post-pub revellers) sometimes put kebab meat on a pizza, producing a culturally-dubious "kebabpizza".
American (where it is sometimes called shish kebab or kebob):
Take-out kebab restaurants are common in some parts of Europe with Döner Kebab said to be the best-selling fast food in Germany. Take-out shish kebab is almost unknown in the US but take-out gyros is quite popular.