Does the counter girl in Haikou Duty Free Shop need to know English?

No, but if it does, it will be your bonus.

Duty-free shop assistants care about whether they can do it for a long time, not spoken English. Meilan airport is very small. Basically, it can be said that the business of each store is quite close.

Duty-free shops refer to shops that have been approved by the General Administration of Customs, set up sales places and supervised warehouses for storing duty-free goods in places approved by People's Republic of China (PRC) and the State Council or their authorized departments, and sell and supply duty-free goods to specific targets.