The Federal Bureau of Covert Vigilance and No-Maj Obliviation (F.B.C.V.N.O.) is a wizarding government agency that seemingly operates under the jurisdiction of the Magical Congress of the United States of America. Judging by its name, it deals with wizarding/No-Maj law enforcement on a federal level, and might be tasked with using spells of concealment and protection in order to hide the magical community from the non-magical population while also working with memory modifications in order to cover things up.
In December 1926, the Federal Bureau of Covert Vigilance and No-Maj Obliviation issued record penalties, something which made headlines on The New York Ghost.
In real life, government bodies with bureau in the name are often a subdivision of a larger agency, and as such, it is possible that despite whatever segregation there is between the magical and non-magical communities of Noth America, that the F.B.C.V.N.O. is actually one of several branches of a parent agency.