The file is the third segment of a multi-part compressed archive containing the PC game Elex II , specifically version 1.0.69.0 . Technical Details

: The "part03" designation indicates that this file is only one piece of a larger set. To extract the game, you must have all other parts (part01, part02, etc.) in the same folder. Origin and Usage

This specific naming convention is typical for or distributed copies found on file-sharing sites. It is often used to break down a large game (which is roughly 45–50 GB) into smaller, more manageable 2 GB or 5 GB chunks for downloading.