Contrary to normal processing of scientific data, whose information is displayed either with curves or contours in 2D, or surfaces in 3D plotting formats, circular functions like phases here need to be dealt with more care, especially near the boundary 2 pi.
Saturation refers to purity.
The more saturated the colour, the less white it is diluted by. Brightness indicates the intensity of the colour on gray scales. It is already shown that phases are closely related to morphology, so phases are what is concerned here.