Spell Slots in D&D 5e: All You Need to Know!
Dungeons & Dragons 5e: Best Magic Items For Sorcerers
See the multiclassing rules to determine your available spell slots. ... For example, if you’re a level 4 Wizard, you can recover up to two levels’ worth of spell slots, regaining either one level 2 spell slot or two level 1 spell slots.
More Spell Slots - Baldur's Gate 3
To cast a spell you need 'spell slots' - so in D&D 5e, you can learn a certain number of spells per day, of certain level like level 1, 2 3 etc.
D&D 5E - Artificer Alchemist / Warlock = Tons of Elixirs?
Character optimization guide for the DnD 5e Artificer's spell list.