When surfing the web without using SSL, any data you submit and any page you view, could potentially be monitored by others. For example if you are viewing this page from your work PC, possibly your employer could see this in the log files of your company firewall. If you use SSL, the data sent between your PC and the website is encrypted, so that an intermediary cannot see the exact data, that is being sent via the internet connection. In general, if a website is available via HTTPS (HTTP via SSL), you should prefer to use this instead of plain HTTP. It might be slightly slower, but with normal PCs and normal network connections, you probably will not even notice the difference.
Since we have several SSL connections via HTTP running on the same machine with different certificates, we also need different ports for these connnections and the default port 443 was already used by another certificate. In some rare cases you might be behind a firewall which will not allow you to connect to port 10443, which we are using. In this case we are sorry, but you will then not be able to view our website via SSL.