Przyklej etykietę zwrotną do przesyłki zwrotnej.

Przyklej is the imperative form, so it means attach / stick on / glue on!

It comes from the verb przykleić (to stick, attach, glue), which is perfective. In instructions, Polish often uses the perfective imperative because it focuses on completing the action:

• przyklejać = to be sticking / to stick repeatedly / imperfective
• przykleić = to stick on successfully, as a completed action / perfective
• przyklej! = stick it on! / attach it!

So this sentence sounds like a normal instruction on a returns label or packing guide.

Because etykietę zwrotną is in the accusative case, not the nominative.

The noun etykieta (label) is the direct object of przyklej — it is the thing being attached. In Polish, direct objects often go into the accusative.

For this feminine singular noun:

• etykieta zwrotna = nominative, the basic dictionary form
• etykietę zwrotną = accusative, used here after the verb

The adjective must match the noun, so both words change:

• etykieta → etykietę
• zwrotna → zwrotną

Because the preposition do requires the genitive case.

Here, do means to in the sense of onto / onto the item / to the package. So the phrase after do has to be genitive:

• przesyłka zwrotna = return shipment/package (nominative)
• do przesyłki zwrotnej = to the return shipment/package (genitive after do)

Again, the adjective agrees with the noun:

• przesyłka → przesyłki
• zwrotna → zwrotnej

Because Polish adjectives change their endings to match the noun’s:

• gender
• number
• case

Both words come from the adjective zwrotny / zwrotna / zwrotne and here both mean something like return-related.

But they must agree with different nouns in different cases:

• etykietę zwrotną → accusative feminine singular
• przesyłki zwrotnej → genitive feminine singular

So the meaning is similar, but the grammar is different.

In this context, zwrotny / zwrotna means return in the sense of for sending something back.

So:

• etykieta zwrotna = return label
• przesyłka zwrotna = return shipment / return parcel

It does not mean returned in a general descriptive sense as much as intended for a return process.

Przesyłka is a general shipping word. It can mean:

• shipment
• parcel
• package
• mail item

The best translation depends on context. In everyday return instructions, English might naturally say:

• Attach the return label to the return package or
• Attach the return label to the return shipment

So przesyłka is a bit broader than just box or package.

Yes. A very common alternative would be something like:

• Naklej etykietę zwrotną na przesyłkę zwrotną.

That uses na (on / onto) instead of do.

The version with do is still understandable and natural in instruction-style language, especially with verbs of attaching. But a learner should know that with labels, stickers, and surfaces, Polish often also uses:

• nakleić coś na coś = to stick something onto something

So both patterns are useful to recognize:

• przykleić coś do czegoś
• nakleić coś na coś

They are similar and often overlap, but there is a slight difference in emphasis:

• przykleić = attach / stick to
• nakleić = stick on / affix onto a surface

In practice, with a label on a parcel, both can work:

• Przyklej etykietę do paczki.
• Naklej etykietę na paczkę.

A learner can think of them like this:

• przy- often suggests to, against, attached to
• na- often suggests onto a surface

But in everyday usage, the difference is not always huge.

Because Polish usually does not need subject pronouns when the verb form already shows the meaning.

Przyklej by itself already tells you this is an instruction addressed to you (singular).

So Polish commonly says:

• Przyklej etykietę... = Attach the label...

not

• Ty przyklej etykietę...

Using ty would usually add emphasis, contrast, or impatience.

Yes, przyklej is the 2nd person singular imperative, so it matches you when speaking directly to one person in an informal or neutral instruction style.

But in written instructions, Polish often uses this short imperative even when no personal tone is intended.

Other possibilities:

• Przyklejcie = attach (plural)
• Proszę przykleić etykietę zwrotną do przesyłki zwrotnej. = Please attach the return label to the return shipment.
• Należy przykleić etykietę zwrotną do przesyłki zwrotnej. = The return label should be attached to the return shipment.

So the original sentence sounds like standard concise instruction language.

Yes. Polish word order is fairly flexible because case endings show the grammatical roles.

The neutral order here is:

• Przyklej etykietę zwrotną do przesyłki zwrotnej.

But you could also hear or see variations such as:

• Do przesyłki zwrotnej przyklej etykietę zwrotną.
• Etykietę zwrotną przyklej do przesyłki zwrotnej.

These alternatives shift emphasis, but the basic meaning stays the same.

For a learner, the original order is the safest and most natural to produce.

Some parts may feel tricky because Polish has consonant clusters and nasal vowels.

A rough guide:

• Przyklej ≈ pshi-KLEY
• etykietę ≈ eh-tih-KYEH-teng
• zwrotną ≈ ZVROT-nong
• przesyłki ≈ psheh-SIHW-kee
• zwrotnej ≈ ZVROT-ney

A few useful notes:

• prz often sounds roughly like psh / pzh
• rz usually sounds like zh
• ł sounds like English w
• ę at the end of a word is often pronounced approximately like -en / -eng / nasal vowel, depending on context
• j sounds like English y

You do not need to pronounce every letter exactly like English spelling suggests; Polish sound patterns are different.

They are:

• przykleić = to attach, stick on
• etykieta = label
• zwrotny / zwrotna / zwrotne = return, return-related
• przesyłka = shipment, parcel, package

In the sentence, they appear in changed forms because of case and agreement:

• przyklej ← from przykleić
• etykietę ← from etykieta
• zwrotną ← from zwrotna
• przesyłki ← from przesyłka
• zwrotnej ← from zwrotna

This is very typical of Polish: learners need to recognize not just dictionary forms, but also the forms words take inside real sentences.