What colour light is showing to oncoming traffic when only the green circle light is lit?

When only the green circle light is lit, it indicates that oncoming traffic is facing a green light as well. This means that they have the right to proceed, whether they are moving straight or making a turn, depending on other traffic regulations or signals present. The green light signals that it is safe for vehicles to move forward, as it allows them to go through the intersection without stopping.

In contrast, other colors such as red or amber signify to oncoming traffic that they must stop or prepare to stop. A red light indicates a complete stop, while an amber light serves as a warning that the light will soon turn red. Therefore, in this scenario, the clear indication of green to oncoming traffic establishes the allowance for movement on their part.