If you access this file through a PHP-enabled webserver (like Apache), it will display a QR-code to initialize an RFC6238 time-based one-time password (as used by Google Authenticator). You can enter test values, hit "Check", and verify that the program logic works.

In this example, the UserSecretKey is a hash of the user IP address. In the real world, the UserSecretKey would be randomly generated when a user initiated this process, and saved in a server database for subsequent verification.