Governors are a feature added in the upcoming Civilization VI: Rise and Fall expansion pack. Here's the lead designer Anton Strenger on the subject: In previous versions of Civilization, “governor” often referred to the AI behavior you could set for a city to act on your behalf. In this expansion, though, they are the opposite. Sending a Governor to a city is a way for the player to make an active decision about the development of one of their cities, and grow in a specific direction. Much like how districts operate in the base game, Governors are a way to specialize your cities. The difference: Governors have their own set of unique powerful bonuses and can move between controlled cities.