Na trybunach powinno się siedzieć spokojnie, kiedy słychać gwizdek sędziego.

Na trybunach means in the stands / on the bleachers at a stadium or sports venue.

The form trybunach is the locative plural of trybuny. After na:

• with location, Polish usually uses the locative
• with movement toward a place, Polish usually uses the accusative

So:

• na trybunach = in/on the stands already there
• na trybuny = onto the stands movement toward them

Here the sentence talks about behavior while being there, so na trybunach is the natural choice.

Because this is an impersonal, general rule.

Powinno się + infinitive means something like:

• one should...
• people should...
• you should... in a general sense
• it is proper to...

So powinno się siedzieć spokojnie is not aimed at one specific person or group. It sounds like a rule of proper behavior.

Compare:

• Powinniśmy siedzieć spokojnie = we should sit calmly
• Powinni siedzieć spokojnie = they should sit calmly
• Powinno się siedzieć spokojnie = people should sit calmly / one should sit calmly

No, not really.

In this sentence, się is not meaning oneself. It is part of an impersonal construction. It helps create the idea of a general statement rather than talking about a specific subject.

So:

• myć się = to wash oneself → truly reflexive
• mówi się, że... = people say that... / it is said that... → impersonal
• powinno się siedzieć spokojnie = one should sit calmly → impersonal

So here się is grammatical rather than truly reflexive in meaning.

This is about aspect and the kind of action being described.

• siedzieć = to be sitting, to sit, to remain seated → imperfective
• usiąść = to sit down → perfective

The sentence is about the proper state or behavior during a moment: people should be seated / remain seated calmly when the referee’s whistle is heard.

So siedzieć fits better.

Compare:

• powinno się siedzieć spokojnie = one should sit/remain seated calmly
• powinno się usiąść = one should sit down

The second version would focus on the single action of sitting down, not on the ongoing behavior.

Spokojnie is the adverb form of spokojny.

Here it means something like:

• calmly
• quietly
• without causing disturbance
• sometimes even still

So siedzieć spokojnie is not just physically sitting. It suggests calm, orderly behavior.

A useful contrast:

• spokojny kibic = a calm fan adjective
• siedzieć spokojnie = to sit calmly adverb

Słychać is a very common impersonal Polish verb form meaning:

• it can be heard
• one can hear
• is heard

So kiedy słychać gwizdek sędziego means:

• when the referee’s whistle can be heard
• when the referee’s whistle is heard

It fits the general, rule-like tone of the whole sentence.

If you said kiedy słyszysz gwizdek sędziego, that would mean when you hear the referee’s whistle, speaking directly to one person. That is more personal and direct.

So słychać matches the impersonal powinno się very well.

Sędziego is the genitive singular of sędzia and means of the referee or the referee’s.

So:

• gwizdek = whistle
• sędziego = of the referee

Together:

• gwizdek sędziego = the referee’s whistle

Also, in context, gwizdek often refers not just to the object itself but to the sound of the whistle.

One helpful detail: after słychać, the thing heard is treated like the object of hearing. In this sentence gwizdek looks the same as nominative because it is a masculine inanimate noun, and its accusative singular form is identical to its nominative form.

Literally, gwizdek is the whistle as an object.

But in a sentence like słychać gwizdek sędziego, it is naturally understood as the sound of the referee’s whistle.

This is normal in Polish, just as in English we can sometimes say:

• I heard the bell
• I heard the whistle

even though what we really hear is the sound.

It sounds like a general rule or expectation of behavior, not a direct command.

Because of powinno się, the tone is:

• less direct than an imperative
• more like etiquette, policy, or instruction
• somewhat formal or neutral

Compare:

• Siedźcie spokojnie! = Sit calmly! direct command
• Na trybunach powinno się siedzieć spokojnie... = In the stands, one should sit calmly... general rule

So this sentence would fit well in instructions, regulations, or formal guidance.

Yes. Polish word order is fairly flexible, and you can move parts of the sentence to change emphasis.

For example:

• Na trybunach powinno się siedzieć spokojnie, kiedy słychać gwizdek sędziego.
• Kiedy słychać gwizdek sędziego, na trybunach powinno się siedzieć spokojnie.

Both are natural. The second version puts more focus on the time/condition first: when the whistle is heard.

One small note: się usually stays close to the verb area, so powinno się siedzieć sounds much more natural than moving się far away.