It puts the ip address for the site mentioned in the screenshot in your computers dns lookup table. For when they kill the global dns cache and block dns lookups to block said site. It will basically allow you to still access that site without having to perform the dns lookup. Think of a web url as a name in a phone book, with the ip address being the associated phone number. When you navigate to a url, your device hits up a dns server to see what the "phone number" is before sending your request to the ipaddress by url. They have the ability to remove all or select names from the phone book. Rendering a dns lookup useless, and thus preventing you from accessing the site at the ip address. By adding these entries to your host file it will go straight there, without having to get the ip address from a dns server. Effectively bypassing their girlyman attempts to keep you from accessing certain sites.