Vadim M.

Not from the US but we have the same thing here. They control one of the two lanes, which one stays and which one goes

The one on the left lets the left turn lane turn and signals in between the two major directions getting green lights (so if you were in the middle lane, you’d have to wait for the traffic going across the intersection, then the left turns, then you could go)

It’s a light to control the turning lane. We have them in the UK to but normally they have arrows rather than just a light

The left side may be used for direction (such as a left turn) in this case, while the right one could be used for going straight. Very often it is swapped, but I am just going by the picture.

Left is left arrow green bottom, cycles to left arrow yield. The top remains red indicating that the traffic other than the turn lane should remain stopped. Usually both sides get left arrow at the same time, but not always. During left arrow the opposite traffic is stopped.

The dual traffic light is a mix of a standard and left turn light. So it’s a somewhat reserved left turn, where the arrow can be green and you can turn against no traffic, or there can be no arrow and turn if there’s no traffic approaching.