The Wait For File event pauses the project run until something happens to a file.
For an overview of "Wait For..." events, including specifics of the Wait Options, see this topic.
You can choose to wait for one of the following conditions:
File to exist
The project run will continue when the given file has been created.
File to no longer exist
The project run will continue when the given file has been deleted or moved.
File to change
The project run will continue when either the given file's length or modification date has changed, relative to the length and modification date which were observed when the action started.
File to become writable
The project run will continue when the file has its Read Only flag cleared, and is not locked for write access.
In the example screenshot above, if Package.rar is being created when the action runs then the run will pause until the archiving process is finished and the file has been closed.
(Note that even though a file may be writable at the precise moment this action succeeds, it is up to you to ensure that another process does not lock it again before your action can open it.)
File to have Archive flag set
The project run will continue when the file has its Archive (A) bit set.
See the Waiting For Events topic.