The content lock feature protects a page from being edited by another CMS user while you have it locked.
If you have locked a page, it will stay locked until:
you manually unlock it
the lock period of 4 hours has elapsed
a site administrator or approver unlocks it
the page has been published.
Locking a content page
Once you have entered Edit mode on a page, the lock is applied and you will see this message:
This content is now locked against simultaneous editing. The content will remain locked if you navigate away form this page without saving or unlocking it.
Once you've completed your changes, you can save as Draft or Needs Review (if the content is ready to go live).
If you've completed what you had to edit but the page is not ready for publishing (eg you've shared a preview link to get approval before setting to Needs review), you should unlock it. See how to unlock a page below.
Trying to edit a page locked by someone else
If another content editor is editing a page you want to work on, you'll see the following message:
This content is being edited by [username of content editor updating page] and is therefore locked to prevent other users changes. This lock is in place since [x min x sec].
This means that you can't edit a page at the same time as another content editor. You can either:
return to the page later to make your edits
ask the editor to remove the lock.