The editing rights options control which users on the front end can edit the item as it progresses through the workflow. Specific editing rights can be set at each step in the workflow. 

To set the editing rights for a step simply select the step on the canvas, select the Step Properties tab and expand the editing rights section then select the appropriate option.

Options include:

Submitter- The user that creates the item, initiating the workflow.

Approvers- Users with a security level of Editor or Full Control on the item created.

Manager- The direct Manager of the user that creates the item. This corresponds to the Manager metadata field that is defined for that user in their user profile in MyHub.