Learn Hardcore Ukrainian: Щойно вона натисне кнопку ліфта, двері закриються. - As soon as she presses the elevator button, the doors will close.

Ukrainian uses the perfective aspect to highlight a single, completed action that triggers another event. The perfective “present” actually has future meaning. So:

вона натисне = she will press (perfective future)
двері закриються = the doors will close (perfective future)

This is the natural way to say “As soon as she presses…, the doors will close.” English often uses a present in the “once/when” clause, but Ukrainian prefers perfective future for a one-time, completed trigger.

What does щойно mean here? Doesn’t it also mean “just now”?

Yes, щойно has two common uses:

As a subordinator = “as soon as”: Щойно вона натисне…, двері закриються.
As an adverb = “just now/just”: Вона щойно натиснула кнопку. (She has just pressed the button.)

Context and verb form tell you which meaning is intended.

Can I replace щойно with something else like як тільки or тільки-но?

Yes. Near-synonyms:

як тільки = as soon as (very common and neutral)
тільки-но = the moment (slightly more colloquial/lively) All three work here with the same punctuation: Як тільки/Тільки-но вона натисне кнопку ліфта, двері закриються.

Why is there a comma after the first clause?

Because щойно introduces a subordinate time clause. In Ukrainian, subordinate clauses are set off by a comma:

Subordinate first: Щойно …, …
Main clause first: …, щойно …

Can I swap the clause order?

Yes: Двері закриються, щойно вона натисне кнопку ліфта. The meaning and punctuation stay the same.

Why is it натисне кнопку and not натисне на кнопку?

Both are used. Without the preposition is a bit more concise and often considered stylistically preferable: натиснути кнопку. With the preposition is very common in speech: натиснути на кнопку. Neither is wrong.

What cases are кнопку and ліфта?

кнопку: accusative singular (direct object of натисне).
ліфта: genitive singular, forming a noun–noun phrase “button of the elevator” (an attributive genitive), like “кнопка ліфта,” “водій автобуса,” “ручка дверей.”

Why are двері and the verb plural: двері закриються?

Двері (“door/doors”) is plural-only in Ukrainian (pluralia tantum). It always takes plural agreement:

ці двері, нові двері, двері закриються/закрилися. There is no singular form like Russian “дверь.”

What does the -ся in закриються do?

It marks a reflexive/middle voice. Here it makes the verb intransitive: the doors “close (by themselves).”

двері закриються = the doors will close (the process happens to them)
Compare active voice: оператор закриє двері = the operator will close the doors.

Is закриються or зачиняться more natural for doors?

Both are acceptable and common.

зачиняти(ся)/зачинити(ся) is traditionally recommended for doors/windows.
закривати(ся)/закрити(ся) is widely used too. So you can say either двері зачиняться or двері закриються.

Could I use the present for a habitual/general statement?

Yes. For habits/rules, use imperfective present:

Коли вона натискає кнопку ліфта, двері зачиняються/закриваються. With щойно, speakers typically choose perfective to stress the single completed trigger. For a general rule, коли
- present is more natural.

Why doesn’t the verb show gender in вона натисне?

In the present/future, Ukrainian verbs don’t mark gender—only person and number. Gender shows up in the past:

вона натиснула (she pressed), він натиснув (he pressed).

Can щойно be used with the past tense too?

Yes:

Щойно вона натиснула кнопку, двері закрилися. = As soon as she pressed, the doors closed. And as an adverb meaning “just now”:
Вона щойно натиснула кнопку. = She has just pressed the button.

Is кнопка ліфта the only way to say “elevator button”?

It’s a good, general way. Alternatives depend on context:

Outside the elevator (call button): кнопка виклику (ліфта).
Inside the cabin: кнопка в ліфті, кнопка на панелі/пульті. Note that ліфта is genitive; ліфту is dative and wouldn’t be used here.

Can I drop the subject pronoun and say just Щойно натисне кнопку ліфта, двері закриються?

Grammatically yes—Ukrainian allows null subjects. But you usually keep вона unless the subject is crystal-clear from context, because 3rd-person singular without a noun/pronoun can be ambiguous.

What’s the aspectual difference between натискати and натиснути?

натискати: imperfective (ongoing/repeated action) — “to be pressing, to press (habitually).”
натиснути: perfective (single, completed action) — “to press once (and finish).” In your sentence, the one-time, completed press that triggers the doors calls for the perfective: натисне.