Password for App is an iCloud feature that issues a Jicoo-specific password instead of an Apple ID password.

It is always in the following format (4 digit string - 4 digit string - 4 digit string - 4 digit string - 4 digit string).

For details on the procedure for creating a password for App, please refer to the official Apple help page.

https://support.apple.com/ja-jp/HT204397