The mapping tab of the Workflow Designer gives a read-only table view to show the relationships that exist across workflow inputs, task inputs, task outputs and workflow outputs. The task inputs and task outputs sections are displayed by task with the workflow, and these sections can both be collapsed to show only the task names.
NOTE: No edits can be made within the mapping tab, but it gives an easy visual to the relationships between all of these values, without having to check each component in the designer tab.
Workflow Designer Mapping Tab within the UI: