|MadSci Network: Astronomy|
My guess is that you misunderstood what was said. The sun puts out a wide range of wavelengths of light; the amount of energy emitted is different at different wavelengths. The peak of this spectrum, as it is called, is at a wavelength which, when isolated, the normal human eye perceives as green.
That is a far cry from saying the Sun is green; not only is that clearly not true, but no star is green when seen in isolation. Stars, including the sun, have an intrinsically broad wavelength range in which they emit, and such a broad range of wavelengths is always perceived by the eye as relatively weak in color. A star that is red for a star is a long way from being what people would call red if they were speaking of crayons or paints.
The sun seen high in the sky is generally called white; when it's seen lower down near the horizon the atmosphere scatters more and more of the blue light out of it and as a result it can look reddish around sunset. You can find comments about this kind of thing here and here, and some comments about the sensitivity of the eye to color here.
Try the links in the MadSci Library for more information on Astronomy.