Pak jsem šel domů.

Czech often leaves out subject pronouns when they are already clear from the verb form.

In Pak jsem šel domů, the word jsem already tells you it is 1st person singular (I), so já is not necessary.

You could say Pak já jsem šel domů, but that usually adds emphasis, contrast, or emotion, for example:

• On zůstal, ale já jsem šel domů. = He stayed, but I went home.

So in a neutral sentence, leaving out já is completely normal.

Pak means then, after that, or next, depending on context.

It connects this sentence to something that happened earlier. It is a very common everyday word.

A close synonym is potom. In many situations, pak and potom can both be used:

• Pak jsem šel domů.
• Potom jsem šel domů.

Both are natural. Pak is just shorter and very common in speech.

That is how the Czech past tense is formed.

For many verbs, the past tense uses:

• a form of být (to be) as an auxiliary
• plus the past form of the main verb

Here:

• jsem = am / past-tense auxiliary for I
• šel = past form of jít (to go)

Together, jsem šel means I went.

So Czech does not build this past tense in the same way English does. Instead of one word like went, it uses a two-part structure.

Because jsem is a clitic, and clitics in Czech usually go in the second position in the sentence or clause.

So after the first element Pak, the clitic jsem comes next:

• Pak jsem šel domů.

That is the normal word order.

Without pak, you would usually say:

• Šel jsem domů.

So:

• Šel jsem domů. = normal when the sentence starts with the verb
• Pak jsem šel domů. = normal when pak comes first

Pak šel jsem domů sounds wrong in standard Czech.

Yes. In the past tense, Czech verbs agree with the speaker's gender and number.

Šel is the masculine singular form, so it is used if the speaker is male.

If the speaker is female, it becomes:

• Pak jsem šla domů.

Other forms include:

• šli jsme domů = we went home (masculine/mixed group)
• šly jsme domů = we went home (all-female group)

So šel tells you that the speaker is a man or boy.

Because domů expresses movement toward home, while doma expresses location at home.

Compare:

• Jdu domů. = I’m going home.
• Jsem doma. = I’m at home.

So after a verb of motion like šel (went), Czech uses domů, not doma.

This is a very important distinction:

• domů = to home / homeward
• doma = at home

For most learners, the easiest way to learn domů is as a fixed adverb meaning home in the sense of toward home.

Historically, it comes from an older case form, but in modern Czech it is best treated as a set expression used with motion:

• jít domů = to go home
• běžet domů = to run home
• vrátit se domů = to return home

So you do not usually build it productively like an ordinary noun form. Just memorize domů as the normal word for home after verbs of going or moving.

Because jít is used for one specific trip or instance of going, while chodit is usually used for repeated, habitual, or general going/walking.

Here, the sentence describes one event:

• Pak jsem šel domů. = Then I went home.

If you said chodil, it would usually suggest something repeated or habitual, for example:

• Po práci jsem chodil domů pěšky. = After work, I used to walk home.

So šel is the natural choice for a single completed action.

A rough English-friendly pronunciation is:

pahk ysem shel domoo

More precisely:

• Pak → pahk
• jsem → the j sounds like English y in yes
• šel → shel, with š like sh
• domů → domoo, with a long ů sound

A few key points:

• š = sh
• j = y
• ů = long oo
• Stress in Czech is usually on the first syllable of the word

So the rhythm is roughly:

PAK jsem šel DO-mů

Potom jsem šel domů is fine and very natural. It means almost the same as Pak jsem šel domů.

But Pak jsem šel do domu usually does not mean the same thing.

• domů = home
• do domu = into the house/building

So:

• šel domů = went home
• šel do domu = went into the house

If you mean returning home in the usual personal sense, use domů.