It's a cautionary signal to inform you that the light is about to change to red. If you can stop within reason, you're expected to.
A yellow arrow traffic light means that you should yield in the direction you are going. These are often in place when you are turning left.
A yellow traffic light means to slow down or stop completely. When the light is yellow it is about to change to red in a few seconds. Contrary to popular belief by many drivers yellow does not mean speed up.
owdown
On traffic lights it means slow down.
The yellow *traffic* light means to slow down and get ready to stop because it is about to turn to the red light.
On traffic lights it means slow down.
A yellow arrow traffic light means that you should yield in the direction you are going. These are often in place when you are turning left.
Yellow light
By "amber" I assume you mean yellow. A yellow traffic light indicates that your "right of way" is ending within the next couple seconds. When the light turns yellow you shouldn't enter the intersection if you haven't already, unless you've reached "The point of no return". It's not illegal to go through the intersection while the traffic light is yellow, but if you can stop you should, if you can't stop then go through the intersection (determined by your own judgement). A yellow light is basically a warning of a red light coming, where it is illegal to proceed through the intersection. The duration of a yellow light depends on the road the traffic light is governing. For a side road the traffic light may only show a yellow for around 3 seconds, for a major road such as a state road or US Highway, the traffic light may show a yellow for 4-6 seconds. These timings all depend on the road that the traffic light is governing and what the speed limit is for that road.
In the U.S.A it means you have the right of way but proceed with caution.
A traffic signal displaying a steady circular yellow light means that you should use caution when going through the intersection. You have the right away, but watch for other cars.
Yellow, then red is the patterns of the traffic lights.