Could you provide or what its intended purpose is? This would allow me to give you more specific details about its typical contents.
To extract and view the contents (and any included "helpful report" or readme.txt file): : Use 7-Zip (free/open-source) or WinRAR. macOS : Use The Unarchiver or Keka .
: Often refers to "Rompacks" or "Asset Packs" for specific consoles or emulators.