Hjoll is the Felsian concept of Hell. It is a region of Exa where supernals generally considered evil or bad dwell, though this is not always the case. In fact, like any other locale or Abode inside the Argence it can take on the semblance of anything its governing power desires.
While parts of it do resemble pits of ash and hellfire, it can appear as a peaceful forest or a tropical island amidst a placid ocean - all subject to the whim of the supernal, god or sorcerer who reigns over the particular Abode.
It differs from traditional concepts of Hell in that there are no souls of the damned or eternal torment - such things as souls do not exist in Fels' milieu. Hjoll, like anywhere else inside the Argence in Exa, is the product of the Collision.