As a star, our Sun is classified as a yellow dwarf. That's because with a surface temperature of about 6,000°C the peak of its radiation output is at wavelengths that we describe as yellow and it is also not a giant star! In fact it's a pretty average-sized star. The Sun is also middle-aged. In human terms it is about 40 years old.
It contains mostly hydrogen and helium, as well as small amounts of the other elements such as oxygen, carbon, nitrogen, magnesium and iron.
At the core its temperature is about 15,000,000°C. That's much hotter than on the surface, which is about 6,000°C.