Nemam kartu za voz, pa danas ne mogu da putujem.

Serbian often leaves out subject pronouns because the verb ending already shows who the subject is.

• nemam = I don’t have
• ne mogu = I can’t

So ja is unnecessary unless you want emphasis or contrast:

• Ja nemam kartu, a on ima. = I don’t have a ticket, but he does.

In the given sentence, leaving out ja sounds completely natural.

This is a very common learner question.

In Serbian, negation with ne is usually written separately from the verb:

• ne mogu
• ne znam
• ne idem

But a few verbs have special negative forms that are written together. Imati is one of them in everyday use:

• imam → nemam
• imaš → nemaš
• ima → nema

So:

• nemam kartu = I don’t have a ticket
• ne mogu da putujem = I can’t travel

You mostly just have to learn these spelling patterns as part of the verb.

Because kartu is the accusative singular form of karta.

Here, kartu is the direct object of nemam:

• Imam kartu. = I have a ticket.
• Nemam kartu. = I don’t have a ticket.

For many feminine nouns ending in -a, the accusative singular changes -a to -u:

• karta → kartu
• žena → ženu
• knjiga → knjigu

So kartu is required here.

Yes. Karta za voz literally means a ticket for the train, and that is a normal Serbian way to say train ticket.

The preposition za often means for. So:

• karta za voz = ticket for the train
• karta za autobus = ticket for the bus
• karta za koncert = ticket for the concert

This is very natural Serbian.

Because za takes the accusative case, and voz is a masculine inanimate noun. In the singular, masculine inanimate nouns usually have the same form in nominative and accusative.

So:

• nominative: voz
• accusative: voz

That is why you get:

• karta za voz

Compare that with a feminine noun, where the accusative often changes:

• škola → školu
• za školu

Yes, absolutely. It is clear, natural, and very common.

You may also see other expressions depending on context, but karta za voz is one of the most straightforward and useful ways to say it.

For a learner, it is a very good phrase to remember because the same pattern works with many other nouns:

• karta za autobus
• karta za avion
• karta za bioskop

Here pa means something like:

• so
• and so
• therefore
• sometimes just a natural spoken connector like well, so

In this sentence:

• Nemam kartu za voz, pa danas ne mogu da putujem.
• I don’t have a train ticket, so today I can’t travel.

It links the first idea to the consequence in a smooth, conversational way.

Yes, Serbian word order is fairly flexible, and danas could appear in different places.

The given sentence is natural:

• Nemam kartu za voz, pa danas ne mogu da putujem.

But you could also say:

• Danas ne mogu da putujem...
• Ne mogu danas da putujem...

The position can slightly change the rhythm or emphasis, but the meaning stays basically the same.

In your sentence, danas fits nicely after pa and before ne mogu.

In Serbian, after many verbs, especially modal verbs like moći (can / be able to), it is very common to use:

da + present tense

So:

• mogu da putujem = I can travel
• ne mogu da putujem = I can’t travel

This structure often does the job that the infinitive does in English.

English:

• I can travel

Serbian:

• Mogu da putujem

This is one of the most important Serbian sentence patterns to learn.

Yes, that is possible, but ne mogu da putujem is very common and very natural in Serbian.

Both mean essentially the same thing:

• ne mogu da putujem
• ne mogu putovati

The da + present construction is especially common in everyday Serbian. As a learner, it is safest to get very comfortable with that pattern first.

Because after da, Serbian normally uses a present-tense verb form, even when the meaning is about something happening now or later.

So in:

• ne mogu da putujem

the form putujem is grammatically present, but the whole phrase means I can’t travel in the situation being discussed. The time reference comes from the context and from danas.

So danas tells you when:

• today I can’t travel

This is normal Serbian grammar.

They are not the same.

• Ne mogu da putujem = I can’t travel / I am unable to travel
• Ne putujem = I’m not traveling / I do not travel

The first one expresses inability or lack of possibility. The second one simply states that the action is not happening.

In your sentence, the speaker is not just saying they are not traveling; they are saying they cannot travel because they do not have a ticket.

Because Serbian does not have articles like English.

So:

• karta can mean a ticket or the ticket
• voz can mean a train or the train

The exact meaning depends on context.

In this sentence, kartu za voz is naturally understood as a train ticket. English needs an article, but Serbian does not.