:-Welcome1
This port allows you to connect the receiver to a PC (suitable cable required) to enable you to update the receivers software with the latest available.
This may add new features, frequency listings etc.
It can also be used to 'patch' a receiver, this can allow access to channels that would normally require other equipment to watch.
These 'patches' can be found on the Internet at various sites. You will have to search for them.
Hope this helps
Lots of additional information is here on this site - just use the 'search' option at the top.