You find this setting on your LED screen and mine says ONE SHOT because so far that is all I have ever used. One shot is best for still life or subjects which are not moving much.
Then there is Al Focus and Al Servo.
Al focus allows your camera to switch focus when a still object moves.
Al Servo allows focus to maintain itself no matter how far away a moving object is and how close. In other words. you can be photographing a moving train and it will allow focus further away and also as it comes into the station .
I must get out and try those second two settings myself. It is something quite important that in my lessons I seem to have missed.