
CrystalSeas |

I'm assuming you're using the free Paizo character sheets for PF2, Pathfinder Second Edition, found here
PF2 Character Sheet
If so, the 2nd row at the top of page 4, with the heading "Spell Slots Per Day", under the bar through the middle containing numbers, is for spontaneous casters to track spell use.
Prepared casters, who have to decide ahead of time which spells they're going to cast each day, don't need to track "how many". They just track which of their prepared spells they've already used up.
If you look below that section, you will see that each individual spell description has a box that you can check labeled "Prep". Each morning when you prepare your spells, you can put a mark in that box to show it's available to you today. Once you use it, remove the mark.