The campaign “What’s Happening?” occurs on a world on the Material Plane made up of three main continents: Hamshire, Southerland, and Enshrina. It is located in a small solar system made up of an unknown number of planets.
The continents are separated by oceans yet to be named.
There is a North Pole and a South Pole. Both places are uninhabitable by most humanoids due to the harsh cold and treacherous environment.
One thousand years ago, a devastating plague befell the continent of Hamshire.
After that, take a look at your wiki. There is some more helpful info there.