It means your bank account info on file didn't match an active account, so the bank rejected the deposit. Your tenant gets the money back automatically — they don't have to do anything to recover it.
Usually the cause is one of:
A typo in your account or routing number
The bank account has been closed
The routing number doesn't match the bank that holds the account
To fix it, you'll need to update your bank info and have us reconnect it to your tenant's autopay. See the FAQ on How do I update my bank account for Split Pay payouts?.
Once that's done, ask your tenant to send the payment again. The next one should land without issue.