Kurtyna poszła w górę, a publiczność zaczęła klaskać jeszcze przed pierwszą piosenką.

Because kurtyna is a feminine singular noun, and Polish past tense agrees with the subject in gender and number.

• kurtyna = feminine
• past tense of pójść must match it
• so: kurtyna poszła

Compare:

• mężczyzna poszedł = the man went
• kobieta poszła = the woman went
• dziecko poszło = the child went

Even though kurtyna is an object, grammatically it behaves like any other feminine noun.

Yes, literally it means went up, and in this sentence it is a natural idiomatic way to say that the curtain rose.

So:

• kurtyna poszła w górę = the curtain went up / the curtain rose

This is a normal expression in Polish. You could also hear:

• kurtyna się podniosła = the curtain lifted / rose

But poszła w górę sounds very natural and slightly idiomatic, much like English went up.

Because w górę means upward / upwards, focusing on direction, not destination.

• w górę = upward
• na górę = upstairs / to the top / to an upper place

So here the curtain is moving up, not going to an upstairs location.

Examples:

• Patrzył w górę. = He looked up.
• Poszli na górę. = They went upstairs.

In Polish, a often links two actions or situations by moving the story forward or making a slight contrast between them. It is often more natural than i in narration.

Here:

• Kurtyna poszła w górę, a publiczność zaczęła klaskać...

This feels like:

• The curtain went up, and then / while that happened, the audience began to clap.

If you used i, it would not necessarily be wrong, but a sounds more natural in this kind of sentence. Polish a is often broader than English but and does not always imply strong contrast.

Because publiczność is a collective noun in Polish. Grammatically, it is singular, even though it refers to a group of people.

So you say:

• publiczność zaczęła = the audience began

not:

• publiczność zaczęli

This is similar to English the audience, the crowd, or the team, except Polish grammar treats it strictly as singular here.

Polish often uses zacząć + infinitive to mean to begin doing something.

So:

• zaczęła klaskać = began to clap

This construction emphasizes the start of the action.

You could also say:

• publiczność klaskała = the audience was clapping / clapped
• publiczność zaklaskała = the audience burst into applause / started clapping

But zaczęła klaskać is very clear and neutral.

Because after zaczęła (began), Polish usually uses an imperfective infinitive to describe the action that started.

• zaczęła klaskać = began clapping

The focus is:

1. on the beginning of the action, and
2. on the action as an activity in progress

That is why klaskać (imperfective) fits naturally.

A perfective option like zaklaskać can exist in other contexts, but after zacząć the imperfective verb is the standard choice.

Jeszcze has several meanings, and here it means something like already / even in the sense of before that point had been reached.

In this sentence:

• jeszcze przed pierwszą piosenką = even before the first song / already before the first song

So it suggests that the audience started clapping surprisingly early.

Common meanings of jeszcze include:

• still: Jeszcze śpi. = He is still sleeping.
• yet: Jeszcze nie wiem. = I don’t know yet.
• more / another: Jeszcze kawy? = More coffee?
• even / already before: Jeszcze przed świtem = even before dawn

After the preposition przed when it means before in time or place, Polish uses the instrumental case.

So:

• piosenka → piosenką
• pierwsza → pierwszą

That is why you get:

• przed pierwszą piosenką = before the first song

More examples:

• przed koncertem = before the concert
• przed domem = in front of the house
• przed ważnym spotkaniem = before an important meeting

Because adjectives in Polish must agree with the noun they describe in:

• gender
• number
• case

Here the noun piosenka is:

• feminine
• singular
• instrumental after przed

So the adjective must match:

• pierwsza piosenka = nominative
• przed pierwszą piosenką = instrumental

This is standard adjective-noun agreement in Polish.

Yes. Polish word order is flexible, and changing it can shift emphasis.

The original:

• Kurtyna poszła w górę, a publiczność zaczęła klaskać jeszcze przed pierwszą piosenką.

You could also say:

• Kurtyna poszła w górę, a jeszcze przed pierwszą piosenką publiczność zaczęła klaskać.
• Jeszcze przed pierwszą piosenką publiczność zaczęła klaskać, gdy kurtyna poszła w górę.

The original version is natural and neutral. Putting jeszcze przed pierwszą piosenką later in the sentence sounds very normal in spoken and written Polish.

Piosenka means song, so it works well if the performance includes songs specifically.

Other options would slightly change the nuance:

• utwór = piece / musical work; more general, sometimes more formal
• numer = number, act, routine; common in entertainment contexts

So:

• przed pierwszą piosenką = before the first song
• przed pierwszym utworem = before the first piece
• przed pierwszym numerem = before the first act/number

The original sentence suggests a performance where songs are central.

Mostly completed events in sequence, but with a bit of attention to the beginning of an ongoing action.

• poszła is perfective: the curtain went up as a completed event
• zaczęła is perfective: the audience began
• klaskać is imperfective: the action they began was clapping, seen as an activity

So the sentence combines:

1. one completed event,
2. the beginning of another action,
3. and that second action is viewed as something that continued for some time.

This is a very common Polish aspect pattern.