A corral is a pen for horses, cows, or other livestock. If your sheep get out of the corral, you'll have to take the dogs out to help you round them up again.
The word corral comes either from the Spanish word corro, which means ring, or from the Old Portuguese word curral, meaning pen or enclosure. As a verb, corral means to gather up or collect. If you're in charge of the big library book sale, you'll have to corral lots of people into helping you. If you make a defensive circle with wagons or other vehicles, you have also corralled the wagons.