You can select an Owner for Goals, Actions, Numbers, and Reports, and they are responsible for these items. While the Updater is the one who has the data to put in, so they can be assigned when you are setting up Numbers and Reports.

The best example is that a Sales Manager is an Owner of the Number "Weekly Product Sale" as they are responsible for the health of the product sale, while the salesperson is the Updater as they have the sales number to update.