Example:

Input_1  You select a true RED color
Input_2 You select a true YELLOW color

Blending => The amount of YELLOW that will be blended in with your RED.
0 = No Blending and the color stays true RED
.5 Half of between RED and YELLOW
1 = No Blending, all will be true YELLOW

1 gallon of RED paint mixed with 1 gallon of YELLOW paint = 0.5 Blending

And you can do the same Blending of textures connected to Input_1 and Input_2

And, LOL, you can control the Blending via a numerical value or by connecting a texture in the Blending node.

Poser 1, 2, 3, 4, 5, 7, P8 and PPro2010, P9 and PP2012, P10 and PP2014 Game Dev
"Do not drive faster then your angel can fly"!