To protect a page of your website with a password, go to Settings and click Password Protection.
First, select the pages you want to protect and create a password you will require visitors to use to access the page. Click Save Changes when you are done.
Once you save changes, the builder will re-load.
To confirm that pages are protected, go to Edit Pages.
Choose a page and you will see a note that the page is protected.
Click Publish. Here's how a password protected page looks once published: