What do blue green and red mean?

Red and Green make brown. these two colors make brown because they are opposite colors on the color wheel. opposite colors make a brown (muddy like color) with this said, you now know that opposite colors on the color wheel, (colors that are on the same spot just on the other side) when mixed together will always make a brown (muddy like color) for example, yellow is opposite violet on the color wheel, so when mixed together they will make brown!