For me, the best resource is Andreas Antonopolous. His Mastering Bitcoin book is the best resource to get a real in depth knowledge of how the bitcoin protocol works and what a bitcoin actually is. The first two chapters are very accessible and can be read at github for free.
https://github.com/bitcoinbook/bitcoinbook/blob/second_edition/ch01.asciidocIf you want something to listen too and want to absorb some crypto currency knowledge more passively, I recommend listening to Andreas' interviews with Joe Rogan on The Joe Rogan Experience Podcast. They are a very good introduction.