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 APIs in the org.
The 'Policies' tab allows you to manage the Policy-level policies that should be applied whenever a request is made to an API via this Plan.
The 'Change Log' tab shows a history of all the changes made to the Plan. Essentially it is an audit log.