Signing off is a new feature that we have introduced to the Editing process so that we can validate users data for the competitive social features we are realising over the next year.
In order to have one user compete against another we need to make sure users have checked their data and agree that it is correct. It is very much like signing a scorecard after a round of competitive golf.
The signing off process will also have added benefits like giving you the option to include the round into your stats or not. This means if you have played in very bad weather for example and don't want the round to skew your stats you can mark for this round not to be included in the stats but the round isn't deleted, it will still show on the rounds page and all the shots can be viewed but they wouldn't contribute to your average distances etc.