I’ve made an attempt to explain the Piwik terminology. Could you please visit https://docs.google.com/document/d/1aDMRcKwgenUS7mS0npG7qzBVPttb4e2yOuOFJoWK67Q/edit and check it out?
Although, I left the terms below without an explanation:
Distinct search engines
Average visit duration for returning visitors
% returning visits have bounced (left the website after one page)
What do you think about the doc?