我们下个月有20天的假期。
译:We’ve (got) 20 days / 20-day off next month.
时态用将来时不行么?
完全可以用将来时态。
We’ve (got) 20 days off next month.
We’ll have 20 days off next month.
We’ve (got) a 20-day holiday next month.
We’ll have a 20-day holiday next month.