Source: https://developers.google.com/analytics/terms/branding-policy
Publisher Coverage:
Coverage is the percentage of ad fill rate.
Ad Impressions / Ad Requests x 100
Publisher eCPM:
Publisher’s revenue generates from 1000 Pageviews. It is your total estimated revenue from all linked Publisher Accounts (AdSense, Adx& DFP) per 1000 pageviews.
Publisher Impressions:
It is reported when an inindividualAdSense, Adx& DFP) is displayed on your Website.