If you file your taxes through the mail you receive a notification through the mail that you were approved on your refund
If you filed by mail , you can check your status online on the IRS website here: https://ttlc.intuit.com/replies/3301525
It take up to 4 weeks for a mailed return to process. You can contact the IRS at 1-800-829-1040 to see if your return was approved.