Imagine the concept that everyone sees in different colors. For example, the way I see green, you see red, but that's what you were born with so it's normal to you. When you think about it, you can't describe color without using the word of the color that it is. There's no possible way we could ever really tell what another person is seeing. Your grass may appear pink through my eyes but it's what you've seen your whole life so it's normal to you.