Because "124" is a simple numerical name, this file could represent several things depending on where you found it:

Once installed, right-click the file and select "Extract to '124'" to view its contents safely in a new folder.

A file is a compressed archive created with the 7-Zip software. It is similar to a .ZIP or .RAR file but often uses a higher compression ratio, meaning it can make large files much smaller. Common Uses for Generic Names Like "124.7z"