How does a person who's never seen or experienced color understand it?
It's mind-boggling to think about. How do you explain a concept to a person who has no context for it? Go ahead, think about how you would convey blue to someone who has never seen the sky or ocean. How do you convey the beauty of a vibrant sunset without using color?
Tommy Edison, who was born blind, asked a group of people to explain colors to him. It's fascinating to watch them try to get their ideas across without using the color itself, just concepts.
The guys who explain gray and pink have particularly interesting takes on the colors -- who would've thought cotton candy is a better example of gray than pink?