Muszę pobrać plik z folderu, który wysłała mi koleżanka.

Muszę means I have to / I must.

In Polish, after musieć (to have to / must), you normally use the infinitive directly:

• Muszę pobrać = I have to download
• no extra word like English to is needed

The choice between pobrać and pobierać is about aspect:

• pobrać = perfective, a completed one-time action
• pobierać = imperfective, ongoing, repeated, or habitual action

So here Muszę pobrać plik suggests I need to download the file completely / as a single finished action.

Because plik is the direct object of pobrać (to download), so it is in the accusative case.

But plik is a masculine inanimate noun, and in Polish those nouns often look the same in:

• nominative: plik
• accusative: plik

So the form does not visibly change, even though the case has changed grammatically.

Because the preposition z meaning from / out of requires the genitive case.

So:

• folder = base form
• z folderu = from the folder

This is a very common pattern in Polish:

• z domu = from the house
• z pokoju = from the room
• z folderu = from the folder

Both z and ze can mean from (or with, depending on context), but ze is mostly used when pronunciation would otherwise be awkward.

Here, z folderu is easy to pronounce, so plain z is used.

You often get ze before difficult consonant clusters, for example:

• ze szkoły
• ze stołu

But:

• z folderu
• z domu
• z biura

This is a very good question, because the sentence can feel a little ambiguous to a learner.

In: Muszę pobrać plik z folderu, który wysłała mi koleżanka.

the relative clause który wysłała mi koleżanka means which my female friend sent me.

Grammatically, który agrees in gender and number with the noun it refers to. Here both possible nouns are:

• plik — masculine singular
• folder — masculine singular

So on grammar alone, który could in theory point to either one. In practice, because it comes right after folderu, many readers will naturally understand it as referring to folder:

• the folder that my female friend sent me

If you wanted to make it clearly refer to plik, you could rewrite the sentence.

For example:

• Muszę pobrać plik, który wysłała mi koleżanka, z folderu.
• or another clearer rewording depending on the intended meaning

So this is a nice example of how Polish can sometimes be grammatically clear in form, but still a bit ambiguous in reference.

Because Polish normally uses a comma before a relative clause introduced by words like:

• który
• która
• które
• którzy

So:

• folder, który...
• kobieta, która...
• dziecko, które...

This is standard punctuation in Polish.

Because the subject is koleżanka, which is a feminine singular noun.

Polish past tense agrees with the subject in gender and number:

• wysłał = he sent
• wysłała = she sent
• wysłało = it sent
• wysłali / wysłały = they sent

So:

• koleżanka wysłała = a female friend/colleague sent

Mi means to me.

It is the dative form of the pronoun ja (I), used here because wysłać komuś coś means to send something to someone.

So:

• koleżanka wysłała mi folder = my female friend sent me a folder

Compare:

• mnie = a fuller, more stressed form
• mi = a shorter, very common unstressed form

In everyday Polish, mi is extremely common.

Not exactly.

Koleżanka usually means a female friend, colleague, classmate, or acquaintance, depending on context. It is broader than English friend.

It does not always imply a very close emotional friendship.

For a close female friend, Polish often uses:

• przyjaciółka = close female friend

So koleżanka can be:

• a female friend
• a female coworker
• a female classmate
• someone you know fairly well

Context decides the best English translation.

No, Polish word order is relatively flexible, but that does not mean all versions sound equally natural.

This sentence: Muszę pobrać plik z folderu, który wysłała mi koleżanka.

is a natural order if you want to say:

• first the action: I have to download
• then the thing: a file
• then where from: from a folder
• then extra information about the folder

Because Polish uses cases, the grammar still works even if you move things around, but changing the order can change:

• emphasis
• style
• clarity

So Polish word order is flexible, but it is still meaningful.

In a relative clause, który behaves a bit like English which / that / who.

It does two jobs at once:

1. It refers back to a noun.
2. It takes the case required by its role inside the relative clause.

Here, inside który wysłała mi koleżanka, the word który is the direct object of wysłała:

• koleżanka wysłała który = my female friend sent which

So it is in the accusative case.

Because it refers to a masculine singular inanimate noun, the accusative form is który.

That is why you do not see something like którego here.

Yes. In Polish, folder can also mean a brochure / leaflet in some contexts.

However, in this sentence, because you have:

• pobrać plik = download a file
• z folderu = from a folder

the digital meaning is clearly intended:

• folder = computer folder/directory

So context makes it unambiguous here.

A native speaker would usually break it up like this:

• Muszę pobrać plik = I need to download a file
• z folderu = from a folder
• który wysłała mi koleżanka = which my female friend sent me

So the sentence is built from:

1. a modal verb + infinitive
2. a direct object
3. a prepositional phrase
4. a relative clause giving more information

This is a very common Polish sentence pattern, so it is worth getting used to.