Short answers, pulled from the story.
The Low Countries today consist of Belgium, the Netherlands, and Luxembourg, collectively known as Benelux. Parts of northern France and the German regions of East Frisia, Guelders, and Cleves are sometimes also included in the historical definition.
The term Low Countries originated at the court of the Dukes of Burgundy, who called their northern territories les pays de par deça, meaning "the lands over here." Governor Mary of Hungary later used the phrase Pays d'Embas, meaning "lands down here," which evolved into the French Pays-Bas and the equivalent English term Low Countries.
The Seventeen Provinces were the unified territories of the Low Countries created under the Pragmatic Sanction of 1549 by the Habsburg ruler Charles V. They remained together until 1581, when the northern Seven United Provinces declared independence from Habsburg Spain, setting the region on the path toward its modern division.
The Eighty Years' War lasted from 1568 to 1648 and split the Low Countries into two parts. The northern Federated Netherlands, or Belgica Foederata, rebelled against King Philip II of Spain, while the southern Royal Netherlands, or Belgica Regia, remained loyal to the Spanish crown. This division laid the early foundation for today's separate states of Belgium and the Netherlands.
Belgium, the Netherlands, and Luxembourg were all occupied by Germany from May 1940 to early 1945, after Germany's Blitzkrieg tactics rapidly overpowered their defences. Their governments were forced into exile in Britain. In 1944, while in exile, those governments signed the London Customs Convention, which laid the foundation for the Benelux Economic Union, an important forerunner of the EEC and later the EU.
The Wachtendonck Psalms are the oldest surviving written literature from the Low Countries, a collection of 25 psalms that originated in the Moselle-Frankish region around the middle of the 9th century. The blind poet Bernlef, from around 800, is among the earliest named literary figures from the region.