Explain Bernoulli's equation?

It is merely a consequence of the conservation of energy.  It takes energy to alter the speed of a moving object.  If you take a moving fluid that energy must come from a reduction of pressure. F = ma Some force is "used" to accelerate the fluid.  OK why does the speed increase in a smaller cross sectional area?  How else does the fluid get through?  If you put a certain volume in at one point it must pass every other point or be stored somewhere in between.  As there is nowhere to store a limitless amount of fluid then once the steady state is achieved dV/ dt = d(L*A)/ dt = A dl/dt = A*v