Restrict allows you to easily restrict access to the entire post category. When creating new or editing existing post category, you will find a dropdown menu which will allow you to select criteria based on which a certain category should be accessible.
By default, it is set to Everyone which means that category will be accessible to all the users. Apart from this, you can select the following criteria:
Additional options may appear in this dropdown if you have Tickera, WooCommerce or Easy Digital Downloads installed on your website. For this, check out our Integrations documentation.