Information on the location
Themyscira is a fictional island in the DC universes that is primarily inhabited by Amazons. It is Wonder Woman's homeland, and while she is there, she looks after all the Amazon's.
Appearance in the rap battle
This is the location where Wonder Woman rapped part of her first verse. Later in the verse, a meteorite start crashing towards the land. Wonder Woman hits the meteorite before it crashes into the land and transitioned into another background. Wonder Woman also rapped her second verse here, with the sky changed from a bright morning sky to a dusk sky.