Volts and Ampere hours
V (Volt) is a measure of electrical voltage, Ah (Ampere hour) is the measurement unit for battery capacity. NiCd cell voltage is for ex. 1.2 V, therefore rated voltages of batteries are (12, 14.4, 20.4 V …). NiCd battery with voltage 14.4 V has 12 NiCd cells.