...
Streaming TV/Pre-roll/Audio Report:
Video Products metrics:
Completed Views: video player started a video and the video played in its entirety
Completion Rate: Completion rate is the number of fully-completed views divided by the number of started views.
Display reporting metrics:
Conversions: The point at which a recipient of a marketing message performs a desired action. In other words, conversion is simply getting someone to respond to your call-to-action.
...
Conversion Rate: on an average of how often an ad interaction leads to a conversion
Spend: The sum of your spending during this period
Cost/Conv: The average cost of a conversion
Avg. CPC: (Average Cost per Click) is the amount you paid for your ads divided by the total clicks
Impression Share: The impressions you received on Google Search sites divided by the estimated amount of impressions that you were eligible to receive
YouTube Reports
...