Red evaluates to RGBColor[1, 0, 0] -- that is the actual expression representing the color, which is used in all subsequent computations.
When using the notebook interface (the Mathematica frontend), the StandardForm of an RGBColor expression is being typeset or formatted to look like a small colored square, which can also be clicked on to start a dynamic color-picking interface.
This typesetting is not available when using the standalone kernel (wolfram), with e.g. JavaGraphics`, nevertheless the color can be visualized by doing something like
Show[Graphics[{Blend[{Yellow, Pink, Green}], Rectangle[]}]]