It's just a database, but it's distributed, with integrity maintained through public keys

Coins, inventory, cars, loans, art, crypto kitties, sensor logs, records.. anything you'd put in a database, you could instead put into the distributed ledger and forget about it (at a price, the amount of data has to be very small but you can also buy hosting separately). Others can then have assurances about the integrity of that ledger without having to trust you either

The cherry on top is being able to write transform functions (ie programs) that all of the nodes simultaneously run so the ledger state can intelligently change based on conditions