: Be cautious. Files with .7z extensions from unknown sources can contain malware. If you didn't download this from a trusted site, I recommend scanning it with an antivirus before opening.
: If it relates to a "PlayMob" platform (often associated with mobile marketing or gaming integration), use: "Application package and configuration files for the PlayMob platform." playmob.7z
Knowing where you got it or what you expect to be inside will help me write a much more accurate description for you. : Be cautious