Electricity in Poland is 220 Volts, alternating at 50 cycles per second.
If you travel to Poland with a device that does not accept 220 Volts at 50 Hertz, you will need a voltage converter. A voltage converter is required for devices that do not accept this level of electricity. Outlets in Poland typically only accept a plug that has two round pins. A plug adapter is used if a plug has a different shape.