The system has detected that you are using Internet Explorer 11. cPanel & WHM no longer supports Internet Explorer 11. For more information, read the cPanel Blog.
The webmail interface allows you to check your e-mail accounts without needing a separate e-mail program. Your web browser is used to check and read your e-mail message.
Always look for this box when logging into Webmail with your hosting provider so that you know that the login prompt is legitimate.