U našem kupeu bilo je tiše nego u hodniku, pa sam tamo čitala cijelim putem.

Because u means in here, so it describes location, not movement. When u shows location in Croatian, it takes the locative case.

So:

• u našem kupeu = in our compartment
• u hodniku = in the corridor

If there were movement into something, Croatian would normally use the accusative instead.

The dictionary form is kupe, but this noun changes form in some cases. After u for location, it becomes kupeu.

So:

• nominative: kupe
• locative: u kupeu

This is one of those noun patterns that learners usually just have to get used to. Since kupe is a borrowed word, its forms may feel less predictable at first.

This is the Croatian way to say it was quieter. English uses a dummy subject, it, but Croatian does not need one here.

The form bilo is neuter singular and is commonly used in impersonal statements about general conditions, such as:

• Bilo je hladno. = It was cold.
• Bilo je mračno. = It was dark.
• Bilo je tiše. = It was quieter.

So bilo je tiše does not refer to a specific neuter noun; it just expresses the situation.

Because tiše is the comparative form: quieter.

The basic form is:

• tiho = quietly / quiet

The comparative is:

• tiše = more quietly / quieter

In this sentence, the speaker is comparing two places, so the comparative is needed: it was quieter in the compartment than in the corridor.

Nego means than after a comparative.

So:

• tiše nego u hodniku = quieter than in the corridor

Croatian can also use od in some comparisons, especially with straightforward noun phrases, but nego is very natural here because the comparison is really between two situations or locations: in our compartment versus in the corridor.

Here pa means something like so, and so, or then. It connects the second part to the first as a natural consequence.

The logic is:

• it was quieter in the compartment,
• so I read there.

It is a very common and natural connector in Croatian, especially in everyday language.

Croatian often leaves out subject pronouns when the verb already makes the subject clear. So ja = I does not need to be said.

In sam tamo čitala, the speaker is understood from the verb phrase. This is very normal in Croatian. Saying ja is possible, but it usually adds emphasis or contrast.

Yes. Čitala is feminine singular, so it tells you the speaker is female.

A male speaker would say:

• pa sam tamo čitao cijelim putem

Croatian past tense forms agree with the subject in gender and number, so this is an important detail learners need to notice.

Tamo means there. It refers back to u našem kupeu.

Even though the location was already mentioned, Croatian often repeats it with tamo to keep the reference clear or to highlight the place a little:

• it was quieter there,
• so I read there

In English, we might or might not repeat there, but in Croatian this sounds very natural.

Cijelim putem means the whole way or throughout the trip.

It is an instrumental phrase:

• cijelim = instrumental singular of cijeli = whole
• putem = instrumental singular of put = way, journey, road

So literally it is something like for the whole journey / all the way.

Also, this putem is not the preposition putem meaning via / by means of. Here it is simply a noun form used in a fixed expression.