Here is the meaning of IRS Refund Status : Return received, Refund approved vs Refund sent.
Return Received: Your return has been received and is currently being processed.
Refund Approved: Your return has been processed and refund amount approved.
Refund Sent: The date your refund was mailed to you or sent to your bank, or the purchase date of your US Savings Bonds.
You will get to see the status of your refund 24 hours after IRS receives your e-file return or 4 weeks if you have mailed a paper return.
For security reasons, IRS recommends you to close your browser after you have finished accessing your refund status. If you do not log out or close your browser you will be automatically logged out after 15 minutes.