O.o layers, do you mean what each layer blending mode does?
let's see normal, exactly how it looks
dissolve, edges dissolve into bg
darken, darker color over
multiply, base colors multiply w/ lighter color on top
color burn, color applied to dark areas is darkened
linear burn, darkens base color
lighten, light color replaces darker color
screen, base colors lighten w/ lighter color on top
color dodge, color applied to light areas is lightened
linear doge, brightens base color
overlay, multiply or screen depends on base color
soft light, depending shade of gray, color is darkened or lightened
hard light, depending shade of gray, color is multiplied or screened
vivid light, dodges/burns base color depending on blend color
linear light, dodges/burns base color depending on shade of gray
pin light, replaces base color depending on shade of gray
hard mix, combo of vivid light and posterization
hue, uses hue of top layer over base
saturation, like hue, by saturation of top layer is used instead
color, used usually for coloring black/white images
luminosity, uses luminance of top color over base
that took forever to type, lol