clear for landing or takeoff.
stop or give way.
If the aircraft is in flight, a steady green light signal from the control tower means cleared to land. If the aircraft is on the ground, it means cleared for takeoff. If the light is aimed at ground vehicles or foot traffic, steady green means cleared to cross the runway, or proceed.
clear for taxi or return to land
warning- use caution
taxi clear of runway or do not land.
return to ramp
After stopping, you may turn right, unless prohibited by some other sign or signal.
If you mean the light gun signals from the control tower- to vehicles, and aircraft on the ground, get off the runway. For aircraft in flight, runway is unsafe, do not land.
stop: clear the active runway
A red light - steady or flashing - means STOP. A steady amber light means Caution - signal about to change. A flashing amber light means SLOW DOWN.
In darkness or reduced visibility, visible red and green lights on a vessel indicate its orientation and direction of travel. A steady red light on the port (left) side and a steady green light on the starboard (right) side signify that the vessel is underway and facing the observer. If you see both red and green lights, it means you are approaching the bow of the vessel. If only one light is visible, it indicates the vessel's side, helping you assess its direction and take appropriate navigational actions.
A steady yellow signal light at a traffic intersection means that the light is about to turn red, and drivers should prepare to stop safely before the intersection.