Every single transaction is permanently stored in the ledger. For example, think of a component in an assembly such as an air duct for a car, or if you want something a little more imaginative a plastic pituitary gland for a scale model of the human brain.
When that component is first manufactured it will have a barcode, serial number, rfid tag etc… that would be attached to it that would have information on where it was manufactured. So the pituitary gland factory sends a shipment to the brain model assembly plant and each time a pituitary gland is installed it will be scanned/tracked again and this transaction is added to the ledger. So every component in the completed product can be traced all the way to the factory.
Five years later it turns out that the pituitary glands are exploding in classrooms across the country. The transaction ledger can be used to trace the origin of the exploding glands to a factory in Moon Township Pennsylvania, who will be informed that it is their responsibility to finance a recall of their plastic pituitary glands.
So every component used to create a product will have an unique identification marker which will be stored in the ledger.
Another example would be that anyone with permission to the ledger can instantly check on the shipping status of any item.