Visibility % – The Visibility % refers to how visible your the domain, subdomain or URL is in position tracking. It is a metric based on the position of all your keywords.
The aim is to have a steadily increasing visibility, however, this figure will drop if new keywords are added to the campaign as this will increase the keywords while diluting the average position.
If all of your tracked keywords is at position 1, your visibility would be 100%. If none of your keywords rank, your visibility would be 0%.