Well, the title says it all.
This only applies to agencies and master accounts, who have this screen.
The accounts that use the advanced or pro features have data coming also from G. Analytics and G. Webmaster Tools.
We already had data from Google Analytics in the domains overview, and now added also the data from G. Webmaster Tools.
Here is a snapshot of the 2 new columns taken from Webmaster Tools: impressions and visits:
Founder & CEO of SheerSEO