How to exchange Poland money in HK?

Polish currency (Zloty) is not common in Hong Kong. Actually there is no bank can offer this currency in Hong Kong.
Usually, Hong Kong people will change Euro cash in Hong Kong firsy, then use Euro to change Zloty after they arrive Poland. Or you can use Hong Kong's ATM card to withdraw Zloty directly in the ATM (PLUS) machine in Poland

you can click the website it help you.
www.money128.biz and www.fast-beauty.6289.us

for the best rates , change at ur local bank before leave HK.or use credit cards that without charge of foreign exchange rate while u in foreign.