White light is shining on a red apple. the apple

The "white" light is made up of all colors of light.
The apple absorbs all of the colors of light except the red light.
The red light just bounces off of the apple and scatters around.
If you're nearby, some of it enters your eyes, and your visual
mechanism produces the sensation of "red".
This process is a big part of the reason why we call the apple "red".
 
If there was no red in the light that shined on the apple, then
no light would bounce off of it.  The apple would appear black.