[domatic1]

It's a url of an image written on an array inside a smart contract. Something like

nft_owner["http://cloud.com/meme.jpg"] = address

The owner of that address has the permission to interact with that smart contract, only he can transfer it. Basically a type of ownership written on the blockchain that is all.

[azemetre]

Are you allowed to profit off the ownership? Like put the NFT on physical media (shirts, stickers, etc) or license it to others?

[pjc50]

No, the copyright doesn't (automatically) go with it, and there's basically zero legal-system recognition of NFTs.