You can see a green and a red light on the wingtips of an aircraft. Red is always on the left side and green on the right.
In 1800s, the ship captains thought it was a good idea to avoid collisions and here in aviation it is to avoid nautical air collisions so now they’re used in aviation as well, both in aircraft and space craft.
These lights are called “navigation lights.”
The green and red lights are always on, no matter what, and are used to help other aircraft know which direction the aircraft is going, based on whether the other pilot sees red, green or both lights.
The white lights are also on all the time, and flash constantly. These lights are called “anti-collision lights.”