Learn Polish: Musisz zasłonić rolety, zanim pójdziesz spać. - You have to close the blinds before you go to sleep.

After the word zanim (before), Polish uses the tense that logically matches the timeline of events. Since going to sleep will happen in the future, you must use a future tense verb like pójdziesz. English uses the present tense for future events after "before", but Polish is more literal!

I know the word "zamknąć" means "to close". Why can't I say "zamknąć rolety"?

Zamknąć is used for things that physically shut, like doors, windows, or books. Zasłonić literally means "to cover" or "to shield". When dealing with curtains or blinds (rolety), you are pulling them to cover the window, so Polish requires zasłonić.

Is the comma before zanim required?

Yes! In Polish, you almost always need a comma before conjunctions that introduce a new clause (a part of a sentence with its own working verb). Since zanim introduces the clause zanim pójdziesz spać, the comma is mandatory.

Why is the phrase pójdziesz spać instead of just using a future form of "to sleep"?

Just like in English, Polish frequently uses the phrase "to go to sleep" (iść spać) to talk about the action of heading to bed. To put it in the future, you only change the first verb to its future perfective form: pójdziesz (you will go) + spać (to sleep).