The Netherlands is a nation with a long and storied history, but it will steered into Civilization 6 by a ruler of a relatively recent vintage. Queen Wilhelmina ascended to the throne in 1890, when she was just ten years of age, and led the nation through both World Wars before abdicating in 1948—a reign of nearly 58 years.
Wilhelmina's unique leader ability is Radio Oranje, named for her broadcasts to the Dutch resistance during the Second World War, which confers a loyalty bonus to cities originating trade routes to the Netherlands, and also a culture bonus for trade routes established with foreign cities. The Netherlands' unique ability is "Grote Rivieren," which grants major bonuses to Campuses, Theater Squares, and Industrial Zones when built near a river, and its unique improvement is the Polder, a man-made flood plain separated from the sea by dikes that provides food, production and housing from water tiles.
On the military side of things (because it always comes to that, doesn't it?) the Netherlands brings to bear De Zeven Provinciën, a powerful, 80-gun ship of the line that helped make the nation a legitimate naval power in the 17th century. (Historical side note: It's also the name of a class of advanced air defense frigates that recently went into service with the Royal Netherlands Navy.)
The Netherlands will join the Civilization 6 soiree in the Rise and Fall expansion, scheduled for release on February 8, 2018. Here's someone else you'll meet when it gets here, and everything else we know about it so far.