That means the local US consulate believes that USCIS made an error in approving a certain petition. They are sending the peition back to USCIS for a re-examination of the petition and want verification that it is indeed approvable. Basically the State Department challenging competency of USCIS.
Happens on rare occasions. An example would be say USCIS approves a 129-F petition for a foreign fiancee' of a US citizen. The local consulate (having more knowledge of the native laws, bylaws of the beneficiary's country) reckons the beneficiary may still be married and thus not free to marry. That revokes the 129-F since the most important condition of that petition is that both the sponsor and beneficiary are free to marry. In such a case the local US consulate may send the petition baco toe USCIS for a re-evaluation, ofcourse adding their input to it.