A good analogy is a gold backed dollar

Meaning you can exchange the paper for the thing it represents and for that reason the paper price mimics the thing

Example if you own 1 bitcoin worth of etf stock

You can ask for Redemption to receive the physical bitcoin instead

Nuance here being if its cash settled or not but thats how etf works redemption and creation to keep diffrence between etf and spot as minimial or small as possible