This white sign means you:

May turn left only on a green arrow.
May turn left on a green light when it is safe.
Must wait for the solid green light before you turn left.
The Correct Answer and Explanation is :
The correct answer is: May turn left on a green light when it is safe.
Explanation:
The sign in the image indicates that when driving, you are allowed to turn left when the traffic light is green, but only when it is safe to do so. This rule applies to situations where there is no green arrow or specific indication that the left turn is protected.
In traffic signals, a green arrow gives you a protected turn, meaning that you are the only vehicle permitted to proceed in that direction. It signals that oncoming traffic has a red light, and no other vehicles should be in your way, ensuring that you can safely complete the turn without concern for cross-traffic.
However, a standard green light means that traffic in all directions can continue to move, including vehicles traveling straight or turning in other directions. When you see a green light (but not a green arrow), you are still permitted to turn left, but you must yield to oncoming traffic and pedestrians. This means you must wait for a gap in oncoming traffic and make sure it is safe before executing your left turn. This could involve waiting for a few seconds if oncoming vehicles or pedestrians are present.
The important thing to remember is that turning left on a green light is not a guaranteed safe maneuver without further consideration of other traffic. You must assess the flow of traffic, ensure it is clear of any vehicles coming toward you, and be mindful of pedestrians crossing the street. Failure to yield appropriately could result in a traffic violation or even an accident. Therefore, it is essential to always exercise caution when making a left turn on a green light without a protected green arrow.