Hi William, thanks for the question.
It’s saying that it’s most accurate if each social media status updated is tagged for each channel when pasted into bit.ly, e.g. see: http://www.dreamgrow.com/how-to-tag-social-media-links-for-google-analytics/
It’s easiest to integrate a social media management service with GA, e.g. see http://blog.hootsuite.com/hootguide-google-analytics/
Dave