It means you either entered your Social Security number incorrectly or that someone has already used your SSN on a tax return. Make sure you entered the correct SSN in My Info. Correct if you entered it incorrectly, and try to e-file again. If you entered it correctly, then the only way you can file is to print, sign and mail your return. There is no way to e-file with a Social Security number problem.
When you mail a tax return, you need to attach any documents showing tax withheld, such as your W-2’s or any 1099’s. Use a mailing service that will track it, such as UPS or certified mail so you will know the IRS/state received the return.