Jotunheim is an alien world populated by a species known as Frost Giants.
Frost Giants are humanoids who stand about fifteen feet (five meters) tall. They have blue skin and a great tolerance for cold. Even for their size, they are strong and durable: Frost Giants can easily lift thousands of pounds and resist fire from modern firearms. They can tolerate extremely low temperatures, and they can suck the heat out of anything they touch. They can also create weapons out of ice at will.
The Frost Giants appear to have a monarchal government. The last known ruler was Laufey. Their current ruler is unknown.
The Frost Giants have no known fleets or other means of interstellar travel. They once possessed a weapon that could create rays of extreme cold. They were also capable of interstellar/intergalactic teleportation, although they apparently lost that capability when they lost their great weapon to the Asgardians. They typically engage their enemies in close combat, although they can fling sharp shards of ice with enough force to injure Asgardians.
They do not appear to pose a major threat to other civilizations at present, but other civilizations might find invading Jotunheim problematic.