it's a non-exchangeable token. for example, works of art.
When a work of art has value, it can be valued at a very high price.
I think the explanation given in this thread will make you understand and know what NFT you mean.
NFT is a concept work of art that can be sold at the price of cryptocurrency coins so that the realm of NFT is also in the crypto space like people who have sold photos of their artwork on opensea with a benchmark of several Ethereum so the price looks very expensive.