Na drugim torze stał długi pociąg do Krakowa, a nasz przyjechał dopiero po chwili.

Because na can take different cases depending on the meaning.

• na + accusative often shows movement toward something:
  
  • iść na peron = to go onto the platform
• na + locative shows location:
  
  • stać na peronie = to be standing on the platform

Here the train was located on the track, not moving onto it, so Polish uses the locative:

• tor → na torze
• drugi → na drugim

So na drugim torze means on the second track / at platform track 2.

Because adjectives must agree with the noun they describe in case, number, and gender.

Here:

• tor is masculine singular
• after na in a location meaning, Polish uses the locative

• so both words go into the locative:

• drugi tor → na drugim torze

This is normal adjective agreement in Polish.

Because torze is the locative singular form of tor.

For masculine nouns, different cases have different endings:

• nominative: tor
• genitive: toru
• locative: torze

Since na here means location, it requires the locative, so:

• na torze = on the track

toru would be used in other structures, for example:

• nie ma toru = there is no track
• koniec toru = the end of the track

Yes, stał literally means stood, but in Polish it is very natural to use stać for things like trains, cars, buses, or buildings when they are stationary.

So:

• pociąg stał na torze = the train was standing / was there on the track

In English we usually say was standing only for people, but Polish uses stać much more broadly.

This often sounds more natural in Polish than był.

You could say był, but it is less vivid and less specific.

Compare:

• Na drugim torze był długi pociąg do Krakowa
  = There was a long train to Kraków on the second track
• Na drugim torze stał długi pociąg do Krakowa
  = A long train to Kraków was standing there / was stationed there

Stał emphasizes the train’s physical presence in a fixed place. It paints a clearer picture.

Długi is an adjective agreeing with pociąg.

Here pociąg is:

• masculine singular
• nominative

So the adjective also appears in the masculine singular nominative form:

• długi pociąg = a long train

This is the basic dictionary form of the adjective for a masculine noun.

Because do requires the genitive case.

The city name Kraków changes in the genitive:

• nominative: Kraków
• genitive: Krakowa

So:

• pociąg do Krakowa = train to Kraków

This is very common in Polish:

• do Warszawy
• do Gdańska
• do Wrocławia

It means a train going to Kraków.

In Polish, noun + do + place in genitive is a common way to express destination:

• autobus do centrum = bus to the city center
• samolot do Londynu = plane to London
• pociąg do Krakowa = train to Kraków

So it describes the train by where it is headed.

Because Polish often omits a noun when it is obvious from context.

Here nasz means something like:

• nasz pociąg = our train

But since pociąg was already mentioned, Polish can leave it out:

• a nasz przyjechał... = and ours arrived...

English can do something similar:

• That train was for Kraków, and ours arrived later.

So this is a very natural ellipsis.

Both are possible, but nasz przyjechał sounds more natural here because the noun is already understood.

Polish often avoids repeating words unnecessarily. Once pociąg has been introduced, saying only nasz is enough.

This makes the sentence smoother and less repetitive.

Because the understood subject is nasz pociąg.

The noun pociąg is masculine singular, so the past tense verb must agree with it:

• pociąg przyjechał
• nasz [pociąg] przyjechał

In Polish past tense, verbs show gender in the singular:

• przyjechał = masculine
• przyjechała = feminine
• przyjechało = neuter

This is a matter of aspect.

• przyjechał is perfective
• przyjeżdżał is imperfective

Here przyjechał is used because the arrival is seen as a completed event:

• nasz przyjechał = our train arrived

Przyjeżdżał would suggest repeated action, ongoing action, or a different viewpoint, and it would not fit as well here.

Dopiero means something like:

• only
• not until
• only then

In this sentence it adds the idea of lateness or delay from the speaker’s point of view:

• nasz przyjechał dopiero po chwili
  = our train arrived only after a moment / didn’t arrive until a bit later

So dopiero often expresses that something happened later than expected or not earlier.

Po chwili means:

• after a moment
• after a short while

The noun chwila means moment. After po in this time expression, Polish uses the locative:

• chwila → chwili

So:

• po chwili = after a moment

It is a very common expression.

Both a and i can mean and, but they are not always interchangeable.

• i usually simply adds information
• a often introduces a contrast, comparison, or shift

Here the sentence contrasts two trains:

• on the second track there was a long train to Kraków,
• but/as for ours, it arrived only later

So a is the more natural choice because it marks that contrast.

Polish word order is flexible, and the beginning of the sentence often presents the setting or the most important information first.

Starting with Na drugim torze tells us immediately where the scene is happening. Then the sentence introduces what was there:

• Na drugim torze stał długi pociąg...

This word order is very natural in narrative or descriptive Polish.

Yes. Polish allows several variants, for example:

• Długi pociąg do Krakowa stał na drugim torze, a nasz przyjechał dopiero po chwili.

This is grammatically correct, but it changes the emphasis.

• Na drugim torze... emphasizes the location first
• Długi pociąg... emphasizes the train first

The original version sounds natural because it sets the scene before introducing the contrast with nasz.