Wieczorem oglądamy komedię z napisami, bo moja przyjaciółka uczy się polskiego.

Wieczorem is a very common adverbial form meaning in the evening / this evening. Polish often uses this kind of time expression without a preposition.

So:

• wieczorem = in the evening
• rano = in the morning
• nocą = at night

You could sometimes build other expressions with prepositions, but wieczorem is the natural everyday choice here.

Oglądamy is the 1st person plural present tense of oglądać, so it means we watch / we are watching.

The ending -my is the key clue that the subject is we.

Compare:

• oglądam = I watch
• oglądasz = you watch
• ogląda = he/she/it watches
• oglądamy = we watch

It can function as either, depending on context. In Polish, the present tense of an imperfective verb is often used for:

• a general/habitual action, or
• a planned future event

Because the sentence begins with wieczorem, many learners will understand it as something like a plan for later today: We’re watching a comedy this evening.

So this is normal Polish usage.

Because komedia is the direct object of the verb oglądać. In Polish, direct objects often go into the accusative case.

• nominative: komedia
• accusative: komedię

Since komedia is a feminine noun ending in -a, it changes to -ę in the accusative singular.

The preposition z meaning with takes the instrumental case.

So:

• basic form: napisy = subtitles
• after z: z napisami = with subtitles

This is a very common pattern:

• z przyjacielem = with a friend
• z herbatą = with tea
• z napisami = with subtitles

Because napisy means subtitles/captions, which are normally spoken of in the plural in Polish, just as in English.

So:

• napis = an inscription / a caption / a line of text
• napisy = subtitles

Then after z, it becomes instrumental plural:

• z napisami = with subtitles

Both can mean because, but bo is more common in everyday spoken Polish.

• bo = neutral, conversational, very frequent
• ponieważ = more formal or written

In this sentence, bo sounds natural and ordinary: ...bo moja przyjaciółka uczy się polskiego.

This is the subject of the second clause, so it stays in the nominative case.

• moja = my
• przyjaciółka = female friend

Together: moja przyjaciółka = my female friend

Because przyjaciółka is feminine, the possessive adjective also takes the feminine form moja.

Yes. Przyjaciółka is feminine, so it means a female friend.

Compare:

• przyjaciel = male friend
• przyjaciółka = female friend

So the sentence tells us the friend is female.

Because uczyć się means to learn or to study, while uczyć without się usually means to teach.

So:

• uczyć = to teach
• uczyć się = to learn

This is a very important distinction:

• Uczę polskiego. = I teach Polish.
• Uczę się polskiego. = I am learning Polish.

Because uczyć się normally takes the genitive case.

So:

• nominative: polski
• genitive: polskiego

That is why we say:

• uczyć się polskiego = to learn Polish
• uczyć się matematyki = to learn mathematics
• uczyć się historii = to study history

Yes. In this sentence, polskiego clearly means the Polish language, even though the word język is not stated.

Polish often leaves język understood:

• uczę się polskiego = I’m learning Polish
• more explicit: uczę się języka polskiego = I’m learning the Polish language

Both are correct, but the shorter version is very common.

Polish word order is flexible, and putting Wieczorem first emphasizes the time frame: In the evening / This evening.

It sounds natural because time expressions often come early in the sentence.

Other word orders are possible, for example:

• Oglądamy wieczorem komedię z napisami...
• Komedię z napisami oglądamy wieczorem...

But the original version is smooth and very natural.

Yes, but it is usually unnecessary.

Polish verb endings already show the subject:

• oglądamy already means we watch

So:

• Oglądamy komedię... = normal
• My oglądamy komedię... = possible, but more emphatic, like we are the ones watching the comedy

Polish often omits subject pronouns unless there is contrast or emphasis.