The money is held on the Abra wallet. Your Abra wallet is held privately on your phone. The Abra wallet is a non-custodial Bitcoin wallet that allows you to see the value of your funds in any world currency you choose. Abra has no access (ever) to the private keys that reference your funds. The Abra model is 100% peer-to-peer, with no middle man ever holding, managing or touching your funds at any point in any transaction.
In order to safeguard the funds held on your Abra wallet, it's imperative to create a backup and save your backup phrase on a safe place in the event your phone gets broken, stolen or the app gets deleted by accident.