This is the version number. In indie development, this usually signifies that the game is roughly 60% through its planned core content, though many such games remain in "alpha" for years.
To access the game, you need a utility like 7-Zip or WinRAR. You would right-click the file and select "Extract Here." LongTripToYourMoms-0.6.0-pc.Compressed.rar
Indicates this version is compiled specifically for Windows operating systems (containing an .exe file). This is the version number