The same idea is true when the capacitor is discharging. If the capacitor has been charged to 12 volts and then we connect both legs to ground, the capacitor will start discharging but it will take some time for the voltage to go to 0 volts. Below is a graph of what the voltage is in the capacitor while it is discharging. . We can control the speed of the capacitor's charging and discharging using resistors. Capacitors are given values based on how much electricity they can store.
Larger capacitors can store more energy and take more time to charge and discharge.
The values are given in Farads but a Farad is a really large unit of measure for common capacitors. Pf means picofarad and uf means microfarad. A picofarad is 0.000000000001 Farads. So the 33pf capacitor has a value of 33 picofarads or 0.000000000033 Farads. A microfarad is 0.000001 Farads.