Well you can store any information in the data part, and given how hard it is to find a matching piece, it works as a reliable proof without having to trust any one person or company. So for example a criminal who can’t trust regular banks can write “I owe Big Tony 100 schmeckles” and other criminals know it’s genuine, so Big Tony can use those schmeckles to get a gun from Fat Fred, and in return writes “I owe Fat Fred 10 schmeckles”. Think of it as a way to track favors online without anyone being able to say someone made it up.

Now how does one convert between these made up schmeckles into other existing currency? Well, same as any central bank. As long as someone believes that favors to or from Big Tony or Fat fred are worth something, they will give dollars or euros or whatever to someone who already has one, and they can then use those as arcade tokens to e.g. buy drugs or hitmen or other things conventional currency trustees don’t approve of.

So value is directly dependant on the perceived utility of the people who agree to use it, and indirectly on those who then bet on how much utility it will have in the future, buying or selling schmeckles when it looks like Fat Fred’s gonna get an offer he can’t refuse. And that changes the scarcity of schmeckles on its own, which affects their perceived value too.