The TS Kennedy's propeller has 4 blades.
The engine of the ship is connected to the propeller.
The propeller blades displace water to create the forces that move the TS Kennedy forward.
The photo below, taken when the ship was in dry dock, will give you an idea of just how massive the propeller blades are.
High School Followers: Check out the video below to see how the propeller moves the ship.