That doesn’t make it any clearer. Right, sorry. “Non-fungible” more or less means that it’s unique and can’t be replaced with something else. For example, a bitcoin is fungible — trade one for another bitcoin, and you’ll have exactly the same thing. A one-of-a-kind trading card, however, is non-fungible. If you traded it for a different card, you’d have something completely different.
At a very high level, most NFTs are part of the Ethereum blockchain. Ethereum is a cryptocurrency, like bitcoin or dogecoin, but its blockchain also supports these NFTs, which store extra information that makes them work differently from, say, an ETH coin. It is worth noting that other blockchains can implement their own versions of NFTs.
NFTs can really be anything digital (such as drawings, music, your brain downloaded and turned into an AI), but a lot of the current excitement is around using the tech to sell digital art.