think of this (battery) as a water tank.
the faster the speed of water flows out of the tank, (with a wider hose pipe, the hose pipe being current thus voltage), the lesser time it takes for the tank to become empty and the lesser water the tank hold as a result of fast discharge of water; and vice versa.
so the current i.e voltage is the pipe, the amount of water coming out, or going in to the tank, is the charge, i.e Ah and the tank itself is the battery, i.e Kwh.
Thus V x Ah = watts or Kwh.
Hope that helps.