it means exactly what it says - you are not using the latest version of Sins - which is currently 1.13.
As per the manual, all patching is done via Impulse.
You download Impulse, register the game and it detects what files need updating to bring you up to the current version (it does a dynamic delta, so the first time you patch it might be huge as there are lots of changes, the second time may be really small as very few files actualyl changed).
