Select > Extract here (or Extract to "Taste_of_piercing/" to keep it in a folder).
After extracting, look for a .pdf or .html file if it is a text guide, or a .exe / .app file if it is a game. To help you further, could you tell me: Are you having trouble opening the file? Taste_of_piercing.7z
Since .7z files can contain executable files ( .exe ), always practice caution: Select > Extract here (or Extract to "Taste_of_piercing/"