What Do Flags Mean?

This is the flag of the state of New Mexico, often voted to be the most beautiful flag in the world. I wonder why. Many flags around the world are more or less abstract in their symbolism; eg the Union Jack which in itself is a combo of three flags, the red cross of Saint George, the white saltire on blue of Saint Andrew and the red saltire of Saint Patrick's cross or the French tricolor

Maybe the right question is not 'what' flags mean, but 'how' they mean. Does that mean that its a better flag than the others, or that its a different kind of flag that speaks to us directly?