If red means to stop, yellow means to slow down, then green means to __?
Green means to go. In traffic lights, green is used to indicate that it is safe and allowed to proceed with caution. When the green light is on, it means that vehicles, pedestrians, or cyclists can move forward without stopping, provided it is safe to do so.
I have noticed that traffic lights for trains often do not have a regular traffic light and instead the red is at the bottom and there are two yellow lights and no green light instead, what is up with that?