An engine is a machine that burns fuel to make something move. The engine in a car is the motor that makes it go.
Engines power vehicles including cars, trains, airplanes, and boats. While these engines tend to be powered by fuel that's burned, other engines get their power from electricity, which they convert to mechanical energy — fans, power tools, and small appliances all commonly have electric engines. Figuratively, you can also use the word engine to mean "something that's used to bring about a specific result." In your state, for example, tourism might be the main engine of job growth.