To make it easier to understand what an NFT (non-fungible token) is it's better to first explain each element. If something is non- fungible it means that the item can't be replicated and has qualities that are unique and specific to it. Crypto tokens are a type of cryptocurrency that represents an asset.
Even though NFTs are digital tokens and held in a crypto wallet they can't be used to purchase anything but are rather digital collectibles/ an asset which has the ability to gain in value over time. Examples of this are digital art pieces, memes, gifs, music albums, videos, virtual real estate, and even a tweet! Once you purchase an NFT your ownership is guaranteed through a file with a digital signature. In its simplest terms, an NFT is just digital paperwork saying you're the owner of some digital content- but it could very well be the future.