Przed snem przeczytałam jeden rozdział książki, a drugi zostawiłam na jutro.

Because the speaker is female and the sentence is in the past tense, 1st person singular: I did / I have done.

• przeczytałam = I read / I finished reading
• zostawiłam = I left

For a male speaker, these would be:

• przeczytałem
• zostawiłem

So the -łam ending is a strong clue that the speaker is a woman.

Polish usually drops subject pronouns when they are not needed, because the verb form already shows who the subject is.

Here:

• przeczytałam already means I read
• zostawiłam already means I left

So adding ja would usually be unnecessary unless you want emphasis, like:

• Ja przeczytałam jeden rozdział... = I read one chapter...

Przed snem literally means before sleep, but in natural English it is usually before going to sleep or before bed.

The preposition przed often takes the instrumental case, and that is what happens here:

• sen = sleep
• snem = instrumental singular of sen

So:

• przed snem = before sleep / before bed

This is a very common expression.

Because jeden rozdział książki is the direct object of przeczytałam.

• rozdział is a masculine inanimate noun
• in the accusative singular, masculine inanimate nouns usually look the same as the nominative

So:

• nominative: jeden rozdział
• accusative: jeden rozdział

That is why it does not visibly change here.

Because rozdział książki means a chapter of a book.

In Polish, when one noun describes another in this kind of of relationship, the second noun is often put in the genitive:

• rozdział = chapter
• książka = book
• rozdział książki = chapter of a book

So książki is genitive singular of książka.

Because Polish, like English, often omits repeated words when they are obvious from context.

So:

• jeden rozdział książki = one chapter of the book
• drugi = the second one / the other one

The full expanded version would be something like:

• Przed snem przeczytałam jeden rozdział książki, a drugi rozdział książki zostawiłam na jutro.

But that sounds repetitive, so Polish leaves the repeated noun out.

Because rozdział is understood and does not need to be repeated.

Here drugi works almost like the second one or the other one.

This is very common in Polish:

• jeden... drugi... = one... the other...
• pierwszy... drugi... = the first... the second...

Since the omitted noun is rozdział (masculine inanimate), the adjective stays in the matching form: drugi.

Because a often connects two ideas with a slight contrast or comparison, while i is a more neutral and.

Here the sentence means something like:

• I read one chapter, and the second one I left for tomorrow

There is a mild contrast between the two actions:

• one chapter was finished
• the other was postponed

So a sounds very natural.

Very roughly:

• i = and
• a = and / while / but, depending on context

Because in Polish, a coordinating conjunction like a normally has a comma before it when it connects two clauses.

So:

• Przeczytałam..., a zostawiłam...

This is standard Polish punctuation.

This is a question of verb aspect, which is very important in Polish.

• czytać = to read, imperfective
• przeczytać = to read through / to finish reading, perfective

So:

• czytałam jeden rozdział suggests I was reading / I read in a general or ongoing sense
• przeczytałam jeden rozdział means I finished reading one chapter

In this sentence, the speaker completed that chapter, so przeczytałam is the natural choice.

Again, this is aspect:

• zostawić = perfective
• zostawiać = imperfective

Here zostawiłam na jutro means I left it for tomorrow as a completed decision/action.

zostawiałam would suggest something habitual, repeated, or ongoing, which does not fit well here.

It can correspond to both, depending on context.

Polish does not have a separate tense that works exactly like the English present perfect. The Polish past tense often covers both:

• I read
• I have read

So przeczytałam jeden rozdział could be translated as either, depending on the surrounding context. In this sentence, I read one chapter is the most natural English rendering.

Because zostawić na jutro is a common Polish expression meaning to leave something until tomorrow or for tomorrow.

• jutro = tomorrow
• na jutro = for tomorrow / until tomorrow

Compare:

• Zrobię to jutro = I’ll do it tomorrow
• Zostawię to na jutro = I’ll leave it for tomorrow

So the preposition na is part of the meaning here.

It does not literally mean that she physically placed the chapter somewhere tomorrow. It means she postponed it until tomorrow.

So in context:

• drugi zostawiłam na jutro = I left the second one for tomorrow
• more naturally: I saved the second one for tomorrow or I postponed the second one until tomorrow

This is a very normal Polish way to say that something was not done yet and will be done later.

Yes. In this structure, jeden..., a drugi..., it often means:

• one..., and the other...

In this sentence, since we are talking about chapters, English may say either:

• one chapter..., and the second one...
• one chapter..., and the other one...

If the context suggests there were exactly two relevant chapters, the second one fits well. If the emphasis is just on contrast, the other one also works.

Because it agrees with the understood noun rozdział.

• rozdział is masculine singular inanimate
• the adjective must match it in gender, number, and case

Since it is the direct object here, it is in the accusative singular, but for masculine inanimate adjectives, the accusative looks like the nominative:

• drugi rozdział = nominative
• widzę drugi rozdział = accusative

So drugi is exactly the form we expect.

Yes. Polish word order is more flexible than English, because endings carry a lot of grammatical information.

The given sentence is very natural:

• Przed snem przeczytałam jeden rozdział książki, a drugi zostawiłam na jutro.

But other orders are possible for emphasis, for example:

• Jeden rozdział książki przeczytałam przed snem, a drugi zostawiłam na jutro.
• Przed snem jeden rozdział książki przeczytałam, a drugi zostawiłam na jutro.

These variants may sound more marked or emphasize different parts of the sentence.

Usually before bed or before going to sleep.

• before sleep is the literal meaning
• before bed is often the most natural English equivalent

It refers to the time just before someone went to sleep, not exactly at bedtime in a formal sense.

Primarily it means one, but in context it can feel close to one as opposed to the other.

Polish does not have articles like a and the, so jeden sometimes helps structure the sentence in a way that English would express with articles or contrast:

• jeden..., a drugi... = one..., and the other...

So here it is clearly numerical/contrastive rather than just an indefinite article substitute.

Because the sentence describes two completed, bounded actions:

1. she finished reading one chapter
2. she decided to leave the second one for tomorrow

Perfective verbs are used when the speaker presents actions as complete events:

• przeczytałam = I finished reading
• zostawiłam = I left / set aside

If the speaker wanted to emphasize process or repetition instead, imperfective forms would be more likely.

Yes, very natural.

It sounds like something a person would normally say in conversation or writing. The phrasing is straightforward and idiomatic:

• przed snem is a common time expression
• przeczytać rozdział is normal
• zostawić na jutro is a common idiom
• jeden..., a drugi... is a natural contrast pattern

So this is a good model sentence for learners.