When the ball is stationary, you will observe a white light, but when the ball is in motion (in a darkened room), you will see alternating red, blue, and green lights.
Inside the ball are three colored LEDs that rapidly cycle between red, blue and green light. When the ball is stationary, the eye focuses all three colors on the same part of the retina. As a result, our brain interprets this as white light. This is due to the persistence of vision that occurs inside the brain.
The brain remembers each of the different colored lights for about 1/10 of a second. If the light is focused on different parts of the retina, individual colors are seen.