Original: Jötunheimr (often anglicized Jotunheim) is the world (heim 'home, homeland') of the Giants (two types: rock (or hill giants) and frost (or rime giants)) in Norse Mythology.
Simplified: Jötunheimr (or Jotunheim) is the land of the giants in the Norse mythology. Two kinds of giants (or Jotuns) live in Jötunheimr, rock giants and frost giants.