A red traffic light means stop, green means go and yellow means you must stop if you can safely do so.
Arrows indicate whether traffic turning right or left is allowed to go (depending on which direction the arrow is pointed). For example, if the traffic lights are green, but an arrow pointing right is red, then traffic turning right is not allowed to go, but traffic going straight ahead is.
In cases where there are no left, or right arrows, a red light will mean 'stop' for everyone, and a green light will mean 'go' for everyone.
A flashing yellow arrow means you can turn, but watch carefully for pedestrians and give way to them.