Zgnieć zużyte opakowanie.

It is the 2nd person singular imperative of the perfective verb zgnieść. So it is a command addressed to one person: crush it / squash it.

This form is common in instructions, labels, and signs. If you were speaking to several people, you would use zgniećcie.

Because Polish often uses a perfective verb in commands when the action should be done once and to completion.

So zgnieć suggests:

• do it once
• finish the action
• make the packaging crushed, not just start squeezing it

An imperfective command would sound more like focusing on the process or repeated action.

Here it is singular.

Zużyte agrees with opakowanie in:

• gender
• number
• case

Since opakowanie is neuter singular, the adjective also takes the neuter singular form: zużyte.

This ending can also appear in some plural forms, but in this sentence it is clearly singular because it modifies opakowanie.

In this sentence, it functions like an adjective meaning used.

More technically, zużyty is historically a participial form related to the verb zużyć, but for a learner it is easiest to treat it as a normal adjective here.

So there is no finite past tense in the sentence.

It means used, in the sense of already used up / already served its purpose.

With packaging, it often implies something like:

• empty
• no longer needed
• ready to be thrown away or recycled

It does not necessarily mean physically damaged or worn out.

Because opakowanie is a neuter inanimate noun, and for nouns like that, the accusative singular looks the same as the nominative singular.

So although it is grammatically the direct object here, the visible form stays opakowanie.

Opakowanie can mean:

• package
• container
• packaging
• pack

In this kind of instruction, it usually means the used package or container itself — for example a carton, plastic container, or other piece of packaging.

Yes. Polish word order is more flexible than English.

Zgnieć zużyte opakowanie is a very natural order for an instruction. You could also say Zużyte opakowanie zgnieć, but that sounds more marked and puts more focus on zużyte opakowanie.

For signs and instructions, the verb-first version is especially common.

Roughly, it sounds like zg-nyeć, with the whole word said very compactly.

A few things are difficult for English speakers:

• zg- is pronounced together at the start
• gnie- contains a soft ń-like sound
• final ć is a very soft sound, somewhat like a softened ch

There is no exact English equivalent, so the most important thing is to keep it soft and compact.

Approximately zoo-ZHI-teh, with stress on the middle syllable: zu-ŻY-te.

Useful points:

• ż sounds like the s in measure
• y is a separate Polish vowel, not English ee
• the final -te is clearly pronounced

So the rhythm is zu-ŻY-te.