When this option is enabled, an additional Apache virtual host will be created for this virtual server, listening on port 443. This will allow browsers to connect to https://domainname.com/ using SSL encryption, as well as to http://domainname.com/ without encryption.

If possible, an SSL certificate from Let's Encrypt will be requesting as part of the setup process. Otherwise, a self-signed SSL key and certificate will be generated, so that the SSL virtual host can be immediately used. However, you should generate a valid SSL certificate for the domain as soon as possible, so that it can be properly verified by browsers. This can be done on the Manage SSL Certificate page.