When a user starts working on an item contained in the Remote Repository, a lock is appended on it in the Menu tree view in order to prevent other users from concurrently making changes to the same item. This lock system helps to avoid edition conflicts between users sharing the same resources. Other users can still have a read-only access to this item until the lock is released.
Note that if you are working in cluster mode and a lock is added or removed from an item, the last status of the item will be synchronized in all clustered applications as locks are stored in the Talend Administration Center database. For more information about how to work in cluster mode, see Working in cluster mode.