The story takes place in the world of Remnant, which is filled with forces and creatures known as the “Creatures of Grimm”. Prior to the events of the series, mankind waged a battle of survival against the Grimm before discovering the power of a mysterious element called Dust, which allowed them to fight back against the monsters. In the present day, Dust is used to power abilities and weapons. Those who use these abilities to battle the Grimm are known as Huntsmen or Huntresses.
Picked up the RWBY series during one of my many anime binge-watching marathon sessions over the holidays, As a show its unique in its own way and so far the story is better than what most people would expect at first glance, the animation quality/style takes a while to get used to, but goddamn are the fight scenes epic (especially the food fight scene xD), best still its a web series so u can watch for free without having to waiting for it to air in your country >:]
found another trailer while i was at it >.>
Source: RWBY WIKI
Video Source: Rooster Teeth Animation