The file appears to be a compressed archive, likely related to the Mass Effect Legendary Edition (LE) game mods or community patches . The "LE3" typically refers to Mass Effect 3 within the Legendary Edition, and "ST2" may refer to a specific community project like the "Spectre Expansion Mod" or similar stability/texture updates.

: The official, free, open-source tool for this format on Windows. The Unarchiver : A popular free option for macOS users. p7zip : The command-line port for Linux distributions. How to Use the File Download and Install : Get one of the tools above.

: Mod files often contain a ReadMe.txt or .pdf with specific installation steps for the game. 7Z: Zip 7Zip Rar File Manager - Apps on Google Play

Since this is a .7z file, you will need a third-party archiver to open it, as standard Windows and macOS utilities often do not support this format natively. Recommended Tools to Open .7z Files