If you would like to restrict access to your pages you currently have two options in WordPress.
The first is to set the page to Private, this only allows other users added to your site to be able to access the page, they will need to log in before they can view the page. You can set a lower permission level, such as a subscriber, if you are worried about security.
The second option is to Password Protect your page, this allows you to set a single password that you can provide to anyone you’d like to have access, they won’t need to be a user on your site.
To set these permissions you need to edit the page and make changes to the page settings. You’ll see in the top right corner of the interface you have an option for Visibility, if you click Edit you’ll be shown several settings.
The default visibility is “Public” and you can also choose “Private” or “Password Protected” here.
If you choose “Password Protected” a text field will appear where you can enter your desired password. This is the password you’ll share with your users.
Once you’ve made your selections, click OK then Update and your page will now have extra security.