Application.Version
From Xojo Documentation
Read-Only Property (As String )
A short text description for the app. Usually this contains just the version number (such as 1.2.3.4) and is displayed by some operating systems in Get Info or Property windows for the app. This property can be set only in the IDE.
Notes
Typically version numbers are written as 1.2.3.4.
Version is displayed by the file information windows on macOS (Finder, Get Info) and Windows (Windows Explorer, Properties).
Sample Code
Display the short version:
MessageBox(App.Version)