Kv stands for kilovolts and it amounts to 1000 volts while KVA is 1000 volt amps. Hertz on the other hand is the SI unit for frequency and it is equivalent to one cycle per second. You can check out a chart by visiting http://www.generatorjoe.net/html/electricunit.asp.
KV is kiloVolts (1000 x Volts) kVA is kiloVolt-Amps - the multiplication of Volts applied and Amps flowing. This is different from Watts, because the Volts and Amps are not necessarily in phase. Hertz is the number of cycles per second in the voltage waveform.