Mitchell Clark for The Verge has a really good, non-technical FAQ on what an NFT is and how they work:
Sorry, I was busy right-clicking on that Beeple video and downloading the same file the person paid millions of dollars for.
Wow, rude. But yeah, that’s where it gets a bit awkward. You can copy a digital file as many times as you want, including the art that’s included with an NFT.
But NFTs are designed to give you something that can’t be copied: ownership of the work (though the artist can still retain the copyright and reproduction rights, just like with physical artwork). To put it in terms of physical art collecting: anyone can buy a Monet print. But only one person can own the original.
This is exactly where NFTs fall apart for me. If you own an original Monet, you own something the artist touched and directly manipulated. You can see the three-dimensional ridges of the paint, smell the canvas, taste the— you get the point. You lose all of that with a gift store glossy poster reproduction. But digital works are just 1s and 0s, and they copy exactly the same every time. Clark covers all of this and topics like bit rot and climate change other uses for NFTs, like video games. The article is really comprehensive and easy to understand, and answers many of my questions. (Except, you know, how to setup a wallet, which still perplexes/scares me.)