A glaze is a thin transparent veil of color applied over the under painting or over another glaze. The purpose is to enhance the color creating jewel like tones and it can make the colors brilliant.
A glaze can be used to tone down a color patch that is popping or too noticeable. A glaze will enhance and add depth and life to shadow areas and push colors further into the background.
Warm colors are applied to bring an element forward on the picture plain. To push a color toward the background cool tones are glazed over an area. The complementary color grays down the color beneath it. To add luminescence a veil of a transparent white is applied over a highlighted area then more color is glazed over that.
In this stage of my work there may be from 5 to 15 or more layers of glazes applied. I keep adding glazes until the effect is pleasing to my eye. After that happens I will refine the the painting, possibly adding yet more glazes. I will get the glazes resolved and take another picture to post for that stage.