These are locations that you are currently working on and have not yet published.
These are the locations that are active on your site.
Click here to add a new page. (see 'General Tab')
Highlight the location you want to edit, the location can be in either the Inactive or Published Locations columns then click 'Edit'. (see 'Add / Edit Tabs')
Highlight the location you want to delete, the location can be in either the Inactive or Published Locations columns then click 'Delete'.
To make a Inactive location active on your site, highlight the location in the Inactive Locations column and click 'Publish'. You will see the location move over to the Published Locations column.
To make a location inactive highlight the location in the Published Locations column and click 'Deactivate'. You will see the page move over to the Inactive Locations column.