There are 16 blend modes available in CSS: normal (which is the default blend mode and means that no blending is applied), multiply, screen, overlay, darken, lighten, color-dodge, color-burn, hard-light, soft-light, difference, exclusion, hue, saturation, color and luminosity. (For the sake of brevity, I will refrain from going into technical detail about each of these modes, and will recommend this article instead to learn all about them.)
These blend modes will modify the colours of a background image resulting in a different effect for each mode.