Here is the short Description on Underneath Arcana Feats: Drow High Magic. READ THIS guide for Quick information for your D&D.
Drow High Magic (UA: Feats for Races) 5th Edition
Prerequisite: Elf (drow)
You learn more of the spells typical for your people. You learn detect magic and can cast it at will, without expending a spell slot.
You also learn levitate and dispel magic, each of which you can cast once without expending a spell slot.
You regain the ability to cast the spell in this way when you finish a long rest. Charisma is your spellcasting ability for these spells.