Original: The Valkyries are Odin's beautiful battle maidens that went out to the fields of war to select and collect the worthy men who died in battle to come and sit at Odin's table in Valhalla, feasting and battling until they had to fight in the final battle, Ragnarök.
Simplified: Half of the souls of heroes slain in battles will be guided by the Valkyries, battle maidens, to Odin's hall, Valhalla.