A limousine is a fancy car that's driven by a special driver. Some high school kids hire limousines to take them and their friends to the prom.
Some limousines are unusually long, stretched-out versions of regular sedans, while others are merely large and luxurious. The passengers in a limousine sit in the back, sometimes separated from the driver, or chauffeur, by a partition. Wealthy people might own their limousines, but most people rent them for special occasions like weddings. In the US, the word is also used to mean a more ordinary type of hired car: "I'll just take a limousine to the airport."