If you are concern about your WordPress website security, you can change the WordPress page URLs. This will help you to hide your website identify and make the website secure. Changing the page URLs is not a complex task if you use the plugins ".html on Pages".
This plugins will help you to change the page permalinks effectively. It takes only few minutes to set up the plugins and change the pages URL. You can also manually change the page or post URL from the permalink settings. If you are a beginner, this is the way you should follow to add .html extension on your pages.