If your system is configured to enforce password expiry using a "grace period", you will be prompted to change your password as your password expiry date approaches (but given an option to defer the change until a subsequent login), and will be required to change your password once the expiry date occurs.
During the grace period configured for your system until your password expires, this page will be displayed after you log in, informing you of the upcoming expiry, and prompting you to change your password.
During this grace period, you can either change your password, or postpone changing your password until a subsequent login:
Once your password has expired, this page will be displayed when you attempt to log in to the system, requiring you to change your password before being permitted to proceed with your login.
The Welcome page displays, and a message near the top indicates that your password was changed successfully.