A 5-farad capacitor is an electrical component in circuits that can store five amps per second of charge at one volt. A capacitor stores electrical energy by housing two metal plates separated by a non-conducting substance, called a dielectric. A capacitor's storage potential, which is called capacitance, is measured in units called farads; one farad represents a charge capacity of one amp per second flow rate at one volt.
How Stuff Works explains that a capacitor's voltage in a circuit is the same as the battery, because the electrons that flow from the battery charges the capacitor to its limit. One plate connects to the negative of the battery and accepts electrons, becoming negatively charged, while the other plate connects to the positive terminal and loses electrons, becoming positively charged.
The size and shape of a capacitor along with the dielectric material determines how much charge it can hold. The dielectric can be any material, but for specific applications the dielectric is chosen based on the capacitor's function. Capacitors differ from batteries in that they can deplete their entire charge in a fraction of a second, whereas a battery takes several minutes. This makes capacitors better in applications that require a lot of charge in a short amount of time, such as a camera's flash, according to How Stuff Works.