The MixColorNode interpolates the connected colors by a input factor between [-1,1]. E.g. you can use a height map as input factor to tint areas of your landscapes.
|color 1||The first color interpolated by the input factor 1 = 100% ... -1 = 0%|
|color 2||The second color interpolated by the input factor -1 = 100% ... 1 = 0%|
|The mixed color.|