Yes, there are a plethora of learning sources available on the internet, but I will recommend you to learn from the creator itself -Facebook Blueprint. It is an online tutorial for learning everything about Facebook Ads, plus it is 100% free. Facebook Blueprint provides you with detailed knowledge about every FB Ad with appropriate examples. Also, at the end of every session, there is a small quiz to brush up your knowledge, and the beauty of this tutorial is that they have ranked courses according to the user's skills like beginner, intermediate & advance.