The Workflow History (available under the Steps icon within a matter) shows you the Steps that a Matter has been through and the available steps for it to move onto next.
The screen is broken down into three parts:
This section shows the previous steps that the Matter has been through. You can move the Matter back to one of the previous steps by clicking on that step. The previous steps will be shown in light green, the current step will show in a darker green.
This section shows all step options available to move to from the step that the Matter is currently on. Click on any of these to move to that step. These will be displayed in Yellow.
This is displayed to give you an idea of where on the step tree you are and what steps to take to get to the step you want. This section can be hidden by navigating Admin > General > System Preferences