Nadawca wysłał przesyłkę do adresata.

Because it is the direct object of the verb wysłał.

The basic dictionary form is przesyłka. In this sentence, the sender sent what? — przesyłkę, so the noun goes into the accusative case.

For a feminine noun ending in -a, the accusative singular often changes to -ę:

• przesyłka → nominative
• przesyłkę → accusative

So Nadawca wysłał przesyłkę means the subject performed the action on that item.

Because the preposition do requires the genitive case.

The dictionary form is adresat, but after do, it changes:

• adresat → nominative
• adresata → genitive

So:

• do adresata = to the recipient

This is a very common pattern in Polish: many prepositions force a specific case, and do almost always takes the genitive.

Wysłał tells you several things at once:

• it is past tense
• it is 3rd person singular
• it agrees with a masculine subject

So wysłał means he sent or the male sender sent.

Compare:

• wysłał = masculine singular
• wysłała = feminine singular
• wysłało = neuter singular
• wysłali = masculine-personal plural
• wysłały = non-masculine-personal plural

Because the subject is nadawca, the verb appears as wysłał.

Yes. This is a very important Polish verb-aspect difference.

• wysłał is perfective
• wysyłał is imperfective

Here is the basic contrast:

• wysłał = he sent it, with emphasis on the completed result
• wysyłał = he was sending / used to send / sent repeatedly, depending on context

In this sentence, wysłał suggests a completed action: the parcel was sent.

Yes, in many contexts you could also say Nadawca wysłał przesyłkę adresatowi.

Both are possible, but the feel is slightly different:

• do adresata emphasizes the destination or endpoint
• adresatowi treats the recipient more like an indirect object, similar to sent the recipient a parcel

In everyday use, both can be natural. The version with do is especially easy to understand as physical movement toward a destination.

Because Polish has no articles.

English needs words like a, an, and the, but Polish usually expresses definiteness from context instead.

So Nadawca wysłał przesyłkę do adresata could mean:

• The sender sent the parcel to the recipient
• A sender sent a parcel to a recipient

The exact interpretation depends on context, not on articles.

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

The sentence given is a neutral, clear order:

• Nadawca wysłał przesyłkę do adresata.

But you could also hear:

• Przesyłkę wysłał nadawca do adresata.
• Do adresata nadawca wysłał przesyłkę.

These versions are not random; they change emphasis or information structure. English relies heavily on word order for grammar, while Polish often uses it for focus and style.

Grammatically, nadawca is a masculine noun, even though it ends in -a.

That may look surprising to an English speaker, but Polish has a group of masculine nouns with -a endings, especially for people, such as:

• mężczyzna = man
• kolega = male friend
• nadawca = sender

If the sender is specifically female, Polish can use nadawczyni. Then the verb would also change:

• Nadawczyni wysłała przesyłkę do adresata.

However, in formal or administrative language, nadawca may sometimes be used in a general sense on forms and labels.

A few sounds may stand out:

• nadawca ≈ na-DAF-tsa
• wysłał ≈ VISS-wahw
• przesyłkę ≈ pshe-SIUW-keh
• adresata ≈ a-dre-SA-ta

A few key pronunciation notes:

• w sounds like English v
• ł sounds like English w
• sz sounds like English sh
• cz sounds like English ch, but harder
• rz often sounds like zh as in measure
• final ę is often pronounced less strongly than learners expect, often close to e plus some nasal coloring

You do not need to pronounce every letter exactly like English spelling suggests.

Yes, often it can.

Because wysłał already tells us he sent, Polish often omits the subject when it is clear from context:

• Wysłał przesyłkę do adresata.

That is a complete sentence in Polish.

However, keeping nadawca makes the sentence more explicit and can be useful if:

• the subject is new information
• you want contrast
• this is formal or instructional language

So the full sentence is natural, but omission is also very common in Polish.

This sentence is a good mini-example of Polish case usage:

• Nadawca — nominative
  the subject, the one doing the action

• przesyłkę — accusative
  the direct object, the thing being sent

• do adresata — genitive after the preposition do
  the destination/recipient

So the structure is:

• subject in nominative
• object in accusative
• prepositional phrase with genitive

This is one reason Polish can have flexible word order: the endings help show each word’s job in the sentence.