If you know absolutely nothing about blockchain technology and cryptocurrencies, this page will give you some of the nuts-and-bolts basics to help you understand what they are.
To learn about what blockchain is, go to this page.
Here is a good intro video by one of the recommended channels, Crypto Zombie:
What is Bitcoin?
What is a Bitcoin Wallet?
Bitcoin Mining and the Blockchain
The Simple Explanation
The more technical explanation
What are Bitcoin Blocks and Confirmations?
The Path of a Bitcoin From Send to Receive
Crucial Steps to Keeping Your Bitcoins Safe
A few words by Andreas Antonopoulos on “what is bitcoin?” Andreas speaks on a philosophical level (in easy-to-understand terms) that explains bitcoin not only as a “thing” but how it exists as a concept. I’ve found it to be very helpful in understanding why bitcoin (and cryptocurrencies in general) are so paradigm-changing in scope.