W placówce pocztowej pokazuję numer przesyłki i potwierdzenie nadania.

Because the preposition w meaning in / at usually requires the locative case when it refers to location.

So:

• placówka pocztowa = postal facility / post office branch (dictionary form)
• w placówce pocztowej = in / at the postal facility (locative)

Both words change:

• placówka → placówce
• pocztowa → pocztowej

This is very normal in Polish: adjectives must match the noun in case, number, and gender.

Placówka pocztowa is a fairly formal way to say post office branch, postal office, or postal facility.

A learner may already know poczta, which often means:

• post
• mail
• the post office

But placówka pocztowa is a bit more specific and official-sounding: it refers to the physical branch or office of the postal service.

So in everyday speech, someone might simply say na poczcie or w urzędzie pocztowym, but w placówce pocztowej sounds clear and formal.

Pokazuję is the 1st person singular present tense of pokazywać, meaning I show or I am showing.

So:

• pokazywać = to show
• pokazuję = I show

Polish verb endings usually tell you who the subject is, so -ę here marks I.

Compare:

• pokazuję = I show
• pokazujesz = you show
• pokazuje = he/she/it shows

Because in Polish, subject pronouns are often omitted when the verb already makes the subject clear.

Here, pokazuję already means I show, so adding ja is usually unnecessary.

• Pokazuję numer przesyłki... = natural
• Ja pokazuję numer przesyłki... = possible, but usually adds emphasis, like I am the one who shows...

This is very common in Polish.

Numer przesyłki means the shipment/parcel number or tracking number, literally number of the shipment.

The word przesyłki is in the genitive case because it depends on numer.

This is a very common Polish pattern:

• numer telefonu = phone number
• adres e-maila = email address
• koniec filmu = end of the film
• numer przesyłki = shipment number

So:

• numer = number
• przesyłka = shipment / parcel
• numer przesyłki = number of the shipment

Also note that numer here is the direct object of pokazuję, but its form looks the same in nominative and accusative because it is an inanimate masculine noun.

Potwierdzenie nadania means proof/confirmation of posting or proof of dispatch.

Here:

• potwierdzenie = confirmation / proof
• nadanie = posting, sending, dispatching a parcel or letter
• nadania = genitive form, meaning of posting / of dispatch

So the structure is similar to numer przesyłki:

• potwierdzenie czego? → nadania
• literally: confirmation of dispatch

This is the document or receipt showing that the parcel was sent.

They are in the accusative case because they are the direct objects of pokazuję.

I show what?

• numer przesyłki
• potwierdzenie nadania

However, the forms happen to look like the dictionary forms:

• numer (masculine inanimate) has the same form in nominative and accusative singular
• potwierdzenie (neuter) also has the same form in nominative and accusative singular

So even though the case is accusative, you do not see a visible change here.

Because Polish has no articles.

English says things like:

• the parcel number
• a confirmation
• the post office

Polish simply says:

• numer przesyłki
• potwierdzenie nadania
• placówka pocztowa

Whether something means a or the is understood from context.

So this sentence could be interpreted in English with articles, but Polish does not need them.

Yes. Polish word order is more flexible than English because case endings show grammatical roles.

The given sentence is natural and straightforward:

• W placówce pocztowej pokazuję numer przesyłki i potwierdzenie nadania.

But you could also say:

• Pokazuję w placówce pocztowej numer przesyłki i potwierdzenie nadania.
• Numer przesyłki i potwierdzenie nadania pokazuję w placówce pocztowej.

These alternatives shift emphasis a bit:

• starting with W placówce pocztowej emphasizes the place
• starting with Pokazuję emphasizes the action
• starting with Numer przesyłki i potwierdzenie nadania emphasizes what is being shown

The original version sounds natural, especially in step-by-step instructions or descriptions.

It can correspond to both, depending on context.

Polish present tense often covers both:

• I show
• I am showing

So pokazuję could describe:

• a general habit or routine
• what someone is doing right now
• a step in instructions or a process

In a sentence like this, it often sounds like a description of a typical action in a situation: At the post office, I show the tracking number and proof of posting.

This is a very common question.

• przesyłka is a broader, more formal word for a shipment, mail item, or parcel
• paczka usually means package/parcel in a more everyday sense

So:

• numer przesyłki is especially common in postal/courier language and often means tracking number
• paczka is what many people say in everyday conversation for a package

A parcel sent by post or courier can be called a przesyłka, and often also a paczka, depending on context.

It sounds fairly neutral to slightly formal.

What makes it a bit more formal is vocabulary like:

• placówka pocztowa
• przesyłka
• potwierdzenie nadania

In everyday speech, many people might say something simpler like:

• Na poczcie pokazuję numer przesyłki i potwierdzenie nadania.

That said, the original sentence is completely natural, especially in written instructions, official contexts, or careful speech.