If you like videos, there are some that have been really really insightful here:
https://sysadmincasts.com/episodes/43-19-minutes-with-ansible-part-1-4
https://sysadmincasts.com/episodes/45-learning-ansible-with-vagrant-part-2-4
I highly recommend anyone who’s having trouble wrapping their head around Trellis check 'em out.