What’s an Amp Hour (Ah)?
Amp hour, Ampere hour (Ah) is basically the amount of current a certain battery can supply for a certain period of time.
It is a measure of the amperage (strength of electric current) a battery can provide for exactly one hour. In small batteries such, or standard AA sized batteries, the amp hour rating is usually given in milli-amp hours, or (mAh).
See more information here.