32 ft/sec/sec means that after one second it will be falling at 32 ft/sec, after two seconds at 64 ft/sec and after three seconds at 96 ft/sec.
Finding out how far it has fallen after any period of time is a problem for integral calculus, but the answer is the simple formula Distance = 1/2 (the acceleration of gravity) multiplied by the square of the time = (32/2) * 3^2 = 16 * 9 = 144 feet.
