Yes, it can be rather abstract. To begin with, simply think of it as a way to earn interest through staking your crypto into exchange liquidity pools. You earn rewards that are collected from transaction fees charged by the exchanges you are participating in. There are of course other elements, but that’s a good starting point. My early stumbling point was comparing this too closely to traditional banking. Yes there is lending/borrowing but I’m not certain how common it is for people to take loans because of risks that come from volatility.
I’ve been moving very slowly through this myself. The graphic in the article below which was linked to one of the early videos makes a nice demonstration of “financial legos.” Hope this helps.
https://medium.com/pov-crypto/ethereum-the-digital-finance-stack-4ba988c6c14b