An SSL connection means that any data that you send over the Internet is encrypted, so that nobody can view the data while it's being sent.
SSL stands for "secure sockets layer", which is now being replaced by TLS, or "transport security layer", which you can find out more about from the Wikipedia article linked below.
http://en.wikipedia.org/wiki/Secure_Sockets_Layer
Some websites, such as billing websites, bank websites, some social networking websites, such as FaceBook and Twitter, and others give users the option to use SSL or TLS connections, and in some cases, automatically encrypt a user's connection.
If you see an "https://" in your browser's address bar, then your connection and any data being sent to a particular website will be encrypted using SSL or TLS encryption.
If you'd like to disable this feature, however, I would suggest that you look through your phone's security settings to see if there's an option to disallow SSL connections.
Some websites, such as FaceBook and Twitter, also enable users to enable and disable SSL connections when using their websites, so you may want to look in the settings of any websites that are loading with SSL encryption.
Good luck and I hope I helped you!