There are times when other Joomla! administrators of the site leave a page without tapping one of the methods to close it... save & close or close. Subsequently, when a page hasn't been closed, a padlock appears to prevent another administrator's accessing the page(s) to make changes. Great for content management, not so great if the person is uncontactable.
Selecting this menu option allows Joomla! administrators to perform a global check-in of all currently pending or locked items. It then shows the results of the Global Check-in. This is useful, for example, if an Article is locked by a user who opened it for editing and never finished the editing session. In this case, other users are not able to edit this Article. Performing a Global Check-in releases all such items.
Access
This is screen accessible via: Select System → Global Check-in from the drop-down menus.