What does each type of light mean: 

Red Lights

-Driver must come to a full and complete stop
-Many significant crashes occur at red lights because of drivers trying to get through at the last second.
-Right turns on reds – a driver does not have to make a right turn on red, but may after he/she has come to a complete stop and has checked to make sure there is enough space to complete the turn safely and has yielded to any pedestrian or other road user in the crosswalk

Yellow Lights

-The signal is preparing to go from green to yellow
-A driver should clear the intersection if already in the intersection
-A driver should not enter the intersection if not already in the intersection

Green Lights

-Mean to go when the intersection is clear
-Must still yield to any pedestrians or other road users in the crosswalk