VA, kVA, and apparent power, and power factor (what)?

VA is volts times amps? kVA is Kilo Volts times Amps or 1000 x Volts x Amps? what is apparent power? do i need to know anything about this? what is power factor? i just multiple rhe result by PF which reduces the result by some amount for loss? why would someone use VA and in what context please?