Odds on this meaning be gets a vacation day or just the opportunity to take an unpaid day off on a holiday?
Guaranteed it means he gets an unpaid day off for a day that he would’ve normally been scheduled.
Probably something of a guarantee that he can take a paid vacation day on New Year’s Eve. It’s just that this whole thing feels wrong. Maybe it’s my bias against American retailers speaking but making a certain guaranteed vacation day a prize for online reviews feels utterly dystopian to me. It would be less bad if it was an additional vacation day, but this is Walmart we’re talking about.
I struggle putting my feeling into words one-by-one, but this is roughly my sentiment.