Voltage of a cable is 220 kv what does this mean?

The lower-case 'k' in 'kV' (not 'kv') is a multiplier, representing 'kilo', meaning 'a thousand times', and the upper-case 'V' represents 'volts', the SI unit for potential difference. So a '220-kV' cable has a line voltage (voltage between conductors) of 220 kV.