Sun is made up of gases mainly like hydrogen, helium and small amount of other elements like sulphur, magnesium, carbon, neon, iron, oxygen, nickel, chromium and calcium. Temperature on the surface of sun is approximately 5780K giving the sun white color but it often appears yellow to us when we look at the sun from the earth because of the atmospheric scattering of light.
The color yellow that we see is also a purely human interpretation of a collection of radiation that hits the retinae of our eyes and gets processed by our visual cortex.