This page allows you to set the passphrase for the root user. The root user is known in some other systems as the "Administrator" user. This passphrase is used when performing certain administrative tasks on the system, and for system recovery.
It is important that you set a unique passphrase for the root user, as anyone with the root user's passphrase can access any data on your computer. You should write it down and keep it in a safe place.