Elemental Affinity is a Sorcerer feature gained at level 6 in the 2024 SRD. Your draconic magic has an affinity with a damage type associated with dragons.
Your draconic magic has an affinity with a damage type associated with dragons. Choose one of those types: Acid, Cold, Fire, Lightning, or Poison.
You have Resistance to that damage type, and when you cast a spell that deals damage of that type, you can add your Charisma modifier to one damage roll of that spell.