Przedsiębiorca kontroluje przesyłkę zwrotną.

Because some masculine nouns in Polish end in -a. Przedsiębiorca is one of them.

So in this sentence:

• przedsiębiorca = the entrepreneur / business owner
• it is masculine
• it is in the nominative singular because it is the subject of the sentence

This pattern is common with words for people, for example:

• mężczyzna = man
• kolega = male friend / colleague
• poeta = poet

Even though they end in -a, they are still grammatically masculine.

• przedsiębiorca is in the nominative singular
• przesyłkę zwrotną is in the accusative singular

Why?

• The subject of a sentence is usually in the nominative
• The direct object is usually in the accusative

So:

• Przedsiębiorca = who is doing the action?
• kontroluje
• przesyłkę zwrotną = what is being checked/inspected?

Because this phrase is the direct object, so it must be in the accusative.

The base form is:

• przesyłka zwrotna = return shipment / return parcel

In the accusative singular, feminine nouns and adjectives change like this:

• przesyłka → przesyłkę
• zwrotna → zwrotną

So:

• przesyłka zwrotna = nominative
• przesyłkę zwrotną = accusative

The adjective must agree with the noun in:

• gender
• number
• case

Yes, zwrotną is an adjective.

Its dictionary form is zwrotny / zwrotna / zwrotne.
Here it describes przesyłkę.

In this context, przesyłka zwrotna means a return shipment, returned parcel, or shipment being sent back.

That is a very natural Polish way to express the idea. English often uses a noun+noun structure like return shipment, but Polish often uses an adjective+noun structure:

• przesyłka zwrotna

Not usually in the English control sense.

Polish kontrolować often means:

• to inspect
• to check
• to examine
• to monitor

So in this sentence, kontroluje is more naturally understood as:

• checks
• inspects

This is a common false friend for English speakers, because kontrolować does not always mean to control in the same way English does.

Kontroluje is:

• present tense
• 3rd person singular
• from the imperfective verb kontrolować

So it can mean:

• checks
• is checking

depending on context.

Polish present tense often covers both:

• a habitual action: The entrepreneur checks return shipments
• an action happening now: The entrepreneur is checking the return shipment

The aspect matters too:

• kontrolować = imperfective, focusing on the process or repeated action
• a possible perfective partner is skontrolować = to check/inspect completely

Because Polish has no articles.

So Polish does not normally have separate words for:

• a / an
• the

Whether something is the entrepreneur, an entrepreneur, the return shipment, or a return shipment is understood from:

• context
• word order
• the situation being discussed

So Przedsiębiorca kontroluje przesyłkę zwrotną can be translated in different ways depending on context, for example:

• The entrepreneur is checking the return shipment
• An entrepreneur checks a return shipment

Yes. Polish word order is more flexible than English word order because the case endings show each word’s role.

The neutral order here is:

• Przedsiębiorca kontroluje przesyłkę zwrotną.

But you could also say:

• Przesyłkę zwrotną kontroluje przedsiębiorca.

That still means the same basic thing, because:

• przedsiębiorca is still nominative
• przesyłkę zwrotną is still accusative

The difference is mostly emphasis or focus.

• Przedsiębiorca kontroluje przesyłkę zwrotną = neutral
• Przesyłkę zwrotną kontroluje przedsiębiorca = emphasis on the return shipment or on who is checking it

A rough pronunciation guide:

• przedsiębiorca ≈ pshet-shyem-BYOR-tsa
• kontroluje ≈ kon-tro-LU-ye
• przesyłkę ≈ pshe-SIW-kem or pshe-SYUW-kem depending on how narrowly you describe it
• zwrotną ≈ ZVROT-non

A few useful points:

• rz often sounds like zh / sh-like voiced sound
• się in przedsiębiorca is pronounced softly
• ł sounds like English w
• ą at the end of a word is nasal; before pauses it is often heard approximately like on/om, depending on the environment
• stress in Polish is usually on the second-to-last syllable

So the stress is on:

• przed-się-BIOR-ca
• kontro-LU-je
• prze-SYŁ-kę
• ZWROT-ną

In some contexts, yes, but grammatically it is a masculine form.

Traditionally:

• przedsiębiorca = entrepreneur / business owner

In modern Polish, people may also use a specifically feminine form:

• przedsiębiorczyni = female entrepreneur

However, przedsiębiorca can sometimes be used in a more general or official sense, especially in legal or administrative language, where it may refer to a business operator regardless of sex.

So in everyday language, if you clearly mean a woman, many speakers would prefer:

• Przedsiębiorczyni kontroluje przesyłkę zwrotną.

But in formal language, przedsiębiorca may still be used generically.

The dictionary forms are:

• przedsiębiorca → already in dictionary form
• kontroluje → kontrolować
• przesyłkę → przesyłka
• zwrotną → zwrotna (or the full adjective entry zwrotny)

So if you were looking them up, you would search for:

• przedsiębiorca
• kontrolować
• przesyłka
• zwrotny