attunement slots
DS 3 - Dark Souls 3 Character Planner
Your attunement level determines the number of attunement slots (or spells) that you can carry at a given time. It also increases your focus power.
Attunement: A Solution Without A Problem
One thing I've been having trouble figuring out though is which items should require attunement.
Attunement? - Dark Souls - GameFAQs
For other uses, see Attunement (disambiguation). Attunement is a stat in Dark Souls. This stat governs how many Attunement slots the player has, which in turn allows players to equip and use more types of magic at once.