If you’re coming from Ruby, I highly recommend Dave’s Programming Elixir (Pragprog) (PE) and @sasajuric’s Elixir In Action (Manning) (EIA) and read them as I did - see my reviews in their respective threads for details.
You will probably also want to read Programming Phoenix (Pragprog) (though I’d wait for the 1.4 version - that’s what I’m doing) and then Functional Web Development with Elixir, OTP, and Phoenix (Pragprog) (I might be starting on this myself soon).
I highly recommend PragDave’s course as per @Architect’s post above too (after PE and EIA) - I LOVED this course (again, see my review!)
There are also lots and lots of other awesome Books and Courses too - check out their threads and the reviews in them 
Welcome to the community! I’m sure you’ll love it here 
