Locking Page Variants
Before editing a page variant, you should lock the page variant. Locking prevents the page variant from being edited by other users in parallel. The page variant lock can be released manually. It is released automatically after the configured lock interval has expired. For details about how to configure the page variant lock interval, see Defining Content Lock Period.
Basically, there are two ways to lock page variants: either directly from the page variant list, or via the page variant detail view.