When your e-filed return comes back as rejected, it just means that the IRS has sent your return back to you for correction. Something like a mistyped number that doesn't match the IRS database can trigger a rejection.
Sometimes a rejection can be a blessing in disguise. For example, if you got another W-2 in the mail after you e-filed and your return was rejected, you can simply add the W-2 to your return before you resubmit it, instead of dealing with the hassle of amending an accepted return.
To fix your reject, sign back in to TurboTax and follow the instructions to correct the error. If you need more help, search for your error code to find an article with detailed instructions.