What is revealed by the red color of the super giant star called Betelgeuse?

Answer 1

Its temperature. Red stars are stars with a cooler temperature, typically because the outer layers are much farther from the center of the star, where the fusion actually occurs. Most "main sequence stars" like the Sun are destined to enter a red giant phase as they exhaust their supply of hydrogen, and they begin to expand as reactions occur around an inert helium core.