A popular open-source alternative that can extract RAR files. The Unarchiver: A common choice for Mac users.
Depending on where you encountered this file, the "D12" might refer to: D12andBonus.rar
To see the actual contents of the "D12" and "Bonus" sections, you must "extract" them using specialized software. A popular open-source alternative that can extract RAR files
RAR files can bundle multiple folders and documents into a single, smaller file to save disk space or speed up transfers. D12andBonus.rar