Gaining Resource from any source grants {#} more Resource than normal.
A resource is gathered in different ways depending on class and each skill has a different resource cost. For example, Mana or Fury are resource pools.
The Barbarian uses Fury
The Druid uses uses Spirit
The Rogue uses Energy
The Necromancer uses Essence and Corpses
The Sorceress uses Mana
Diablo 4 follows the same pattern as Diablo 3, with each class having its own Unique resource.