That means that your PHP configuration or server has disabled cURL. cURL is required for almost all of our functionality and is used to communicate with other servers, like Facebook.
You'll need to contact your hosting company and have them enable cURL on your website as it's required for Facebook authentication, our Autotune tool, and quite a bit more.
I hope that helps explain, but if you have any other questions, don't hesitate to ask.
Thanks,
Alex