This is the plan details page. Use this page to modify the Plan's meta-data and policies. Once you have fully configured the Plan, don't forget to "Lock" it so that it can be used by Services in the org.
The 'Policies' tab allows you to manage the Policy-level policies that should be applied whenever a request is made to a Service via this Plan.
The 'Activity' tab shows a history of all the changes made to the Plan. Essentially it is an audit log.