Mission Destination:

The Operative was an agent of the Union of Allied Planets government. Similar to a black ops agent, the Operative’s work was not acknowledged by the government. He didn’t officially exist; he gave up his name upon becoming an operative, and he did not hold an official rank in the Alliance.

His status as an operative could get him access to most (possibly all) Alliance facilities as well as respect from those who knew what an operative was. He had been highly trained in close armed and unarmed combat. Until he had his faith broken, he was unswervingly devoted to his cause.

Source: https://firefly.fandom.com/wiki/Operative