A barbecue (correct spelling!!) is a way to cook food outside, usually over wood or charcoal, but gas barbecues are often seen too. The sort of food cooked is often meat such as pork or beef steak, but lots of other things too: sausages, fish, beefburgers or corn cobs. The food is supported on a metal 'grill' above the heat. The method of cooking, the apparatus it is cooked on and the social event are all called a barbecue. Big salads, drinks and overeating usually accompany it.
Barbecues are often used to cook street food, worldwide.
BBQ at my place tomorrow - all welcome :)