I should have put more effort into explaining the answer, for anyone else the input settings allow you to easily map input from various devices (keyboard, mouse, gamepad etc.) to a named action. In the picture I posted, the actions name is MouseUp and it is mapped to the players mouse moving in the y direction (up and down).
My scale is set to 1 when I move my mouse upwards it will result in a positive value and when I move it down it will be a negative value. If I were to change my scale to be -1 it will be a negative value when move my mouse up and positive when I move my mouse down.
We can then refer to that action using the name MouseUp in blueprints or code.
It’s useful because by having human friendly names it makes our gamelogic easier to read, lets us change the controls for our game from one place rather than everywhere we use the control and lets us easily bind multiple buttons to one action. This is a nice introduction to inputs IMO Input Action And Axis Mappings In UE4 - Unreal Engine .