This message will appear when any item in the system is not properly checked-in (saved).
The system allows of multiple admins for the same company to access parts of the back office at the same time. When an admin opens an item like Private tours, Cars, Orders etc. to edit the item is checked-out (locked) which means that no one else can edit the item until it's checked-in (saved by the admin editing it).
If you open an item and don't Save it for any reason - go to another page without Saving, close browser window, lose internet connection etc., then the system will leave the item Checked-out (locked). Next time you come back to this section you will see a padlock icon in front of the item in items list view. You can easily fix this (unlock the item) by selecting the checkbox in front and clicking on CHECK-IN (unlock) button in the top toolbar.
Now you will be able to Edit the item again. Don't forget to Save your work after you have finished editing.