What does the hotel cashier mean by taking a white night off?

White refers to day shift, night refers to night shift, and rest refers to rest.

There are two explanations for what you said:

1, white night off: there is a shift one night the day before,

White night off: two shifts and one night the day before.

2、

Day shift rest: one day in day shift, one day in night shift, and then one day off.

White night off: white shift, night shift, two days off.