Explaining a complex idea using only words is tricky. Even describing simple things exactly can be hard.
Think of an inverted isosceles triangle that has an apex of 35 degrees. Colour it in with the colour that has the hex value #00a5ff. Here's a hint: that's a greenish blue.
Now, scroll down.
Is this what you have in your head?
Probably not exactly. Maybe not even close.
And I bet that if we compared notes, none of us would have come up with the exact same triangle.
But if, instead of describing the triangle to you, I had just shown it, how much simpler would that have been?