Jutro jadę do Krakowa pociągiem.

Because in Polish, the present tense of an imperfective verb often refers to a planned future action, especially when a time word like jutro already makes the future clear.

So Jutro jadę do Krakowa is very natural and means something like:

• I’m going to Kraków tomorrow
• Tomorrow I’m going to Kraków

It suggests a plan or arrangement.

A closely related form is pojadę, as in Jutro pojadę do Krakowa pociągiem. That is also correct, but it sounds more like a straightforward future statement. Jadę jutro often feels a bit more like I’m going tomorrow.

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

Here, jadę ends in -ę, which tells you it means I go / I’m going.

So:

• Jadę = I’m going
• Ja jadę = I’m going too, but with extra emphasis, contrast, or emotion

You would use ja only if you want to stress it, for example:

• Ja jadę do Krakowa, a on zostaje w domu.
  I’m going to Kraków, and he is staying home.

Because the preposition do requires the genitive case.

The dictionary form is Kraków, but after do it changes to Krakowa.

So:

• Kraków = nominative, basic form
• do Krakowa = to Kraków

This is very common with place names after do.

For example:

• do Warszawy = to Warsaw
• do Gdańska = to Gdańsk
• do Krakowa = to Kraków

Because Polish often uses the instrumental case to express the means of transport.

So:

• pociąg = train
• pociągiem = by train

This pattern is very common:

• jadę autobusem = I’m going by bus
• jadę samochodem = I’m going by car
• jadę tramwajem = I’m going by tram
• jadę pociągiem = I’m going by train

So pociągiem is not a different word; it is the instrumental form of pociąg.

Because jechać means to go/travel by vehicle, while iść means to go on foot.

So:

• jadę do Krakowa pociągiem = I’m going to Kraków by train
• idę do sklepu = I’m going to the shop, on foot

This distinction is very important in Polish and is much stronger than in English. English uses go for both, but Polish usually chooses different verbs depending on how you travel.

Yes, absolutely.

Both are correct:

• Jutro jadę do Krakowa pociągiem
• Jutro pojadę do Krakowa pociągiem

The difference is mainly about aspect and feel:

• jadę is from an imperfective verb and often sounds like a plan or arrangement already in place
• pojadę is perfective and gives a more standard future meaning: I will go / I will travel

In everyday conversation, jadę jutro is very common when talking about planned travel.

Polish word order is fairly flexible, so you can move things around more than in English. The sentence:

• Jutro jadę do Krakowa pociągiem

is natural and puts jutro first for emphasis on time.

Other possible orders include:

• Jadę jutro do Krakowa pociągiem
• Do Krakowa jadę jutro pociągiem
• Pociągiem jadę jutro do Krakowa

These all mean basically the same thing, but the emphasis changes slightly.

In your sentence, the focus feels like: Tomorrow, I’m going to Kraków by train.

No. Polish does not have articles like a/an or the.

So pociągiem can mean:

• by train
• by the train
• sometimes, depending on context, something like on a train

The exact meaning comes from context, not from articles.

That is why the Polish sentence can be shorter than the English one.

A rough guide:

• jadę sounds approximately like YA-deh
  The j in Polish sounds like English y in yes.
• pociągiem sounds roughly like po-CHYON-gyem

A few helpful details:

• ą is a nasal vowel, somewhat like on said through the nose
• ę is also nasal, though in normal speech its pronunciation can vary depending on what comes after it
• ci before a vowel often sounds like a soft ch / ć-type sound

You do not need to pronounce the nasal vowels perfectly at first to be understood, but it is good to notice that ą and ę are special Polish sounds.

Putting jutro first highlights the time and makes it the starting point of the message.

So:

• Jutro jadę do Krakowa pociągiem = Tomorrow, I’m going to Kraków by train

This is a very normal way to begin a sentence in Polish when the time is important.

If you put jutro later, the sentence still works:

• Jadę jutro do Krakowa pociągiem

That version sounds slightly less focused on tomorrow specifically.

In this sentence:

• Krakowa is genitive
• pociągiem is instrumental

Why?

• do
  • genitive → do Krakowa
• travel by means of transport often uses the instrumental → pociągiem

So this one sentence is a good example of how Polish endings show grammatical relationships:

• destination after do → genitive
• means of transport → instrumental

That is one of the big differences between Polish and English.