Please see the below FAQ listed on the IRS website:
What is happening when Where’s My Refund? shows my refund’s status as approved?
We’ve approved your refund. We are preparing to send your refund to your bank or directly to you in the mail. This status will tell you when we will send the refund to your bank (if you selected the direct deposit option). Please wait 5 days after we’ve sent the refund to check with your bank about your refund, since banks vary in how and when they credit funds. (It could take several weeks before you receive a mailed refund check.)
Tax Season Refund Frequently Asked Questions