A flashing red light indicates that you must stop your vehicle before entering the intersection or crosswalk and remain stopped until the signal turns green. In some locations, such as railroad crossings, an automatic gate comes down when the flashing red light is triggered to prevent pedestrians from accidentally being hit by oncoming trains.
When a steady RED light appears, you must come to a complete stop in the rightmost lane and then yield the right of way to all oncoming or crossing traffic, including bicyclists, until the signal turns green. If the road is narrow and there is little space to stop, you can still do so as long as you are careful.
A steady yellow arrow means that the movement permitted by the green arrow or the flashing yellow arrow is about to end, and the signal will soon turn red. You must slow down and prepare to stop before you enter the intersection, if possible.
When the center lane of a highway is marked with a green arrow, you may proceed in the direction the arrow points. If the other lanes are shown with a green arrow, you can move into them without stopping as long as there is no other sign that prohibits it.
In other situations, a steady YELLOW arrow can indicate that turning is allowed. You must yield to oncoming or crossing traffic and pedestrians while you are on the arrow phase, then turn as allowed by your state law. You must also keep your eyes open to be sure there are no other signs that prohibit it.