The Absolute Beginners Guide to Google Analytics
This is a good starting point, if you’ve never used Google Analytics before.
A cheat sheet with key term definitions
If you want to start diving in a bit deeper, I’d like to recommend Neil Patel’s site, and this article in particular: The Ultimate Guide to Google Analytics Resources for 2018
And as always, I encourage you to check out the wealth of courses available at Lynda.com.