paladin spell slots 5e

Whenever you finish a Long Rest, you can replace one spell on your list with another Paladin spell for which you have spell slots.

Character optimization guide for the DnD 5e Druid's spell list.

The Paladin Table above highlights the number of spell slots available at each level. The paladin must select a number of spells equal to their charisma modifier plus half of their paladin level, rounded down.