If you are trying to find where your game is installed to apply a modern patch or mod, you can browse local files directly through your launcher's settings.
This indicates the fifth official title update for GTA V. These updates typically include bug fixes, performance improvements, and security patches. In the context of a cracked release, it is an update applied to a pirated version of the game. 3DMGAME-Grand.Theft.Auto.V.Update.5-v1.0.350.2-...