Kiedy jestem zmęczony, oglądam film w domu.

Because Kiedy jestem zmęczony is a subordinate clause introduced by kiedy. In Polish, subordinate clauses are normally separated with a comma.

So:

• Kiedy jestem zmęczony, oglądam film w domu.

This is standard punctuation, even when English might feel a bit less strict about it.

In Polish, the verb ending usually already tells you who the subject is, so the pronoun is often omitted.

• jestem = I am

The ending -em shows first person singular, so ja is unnecessary unless you want emphasis or contrast.

Compare:

• Jestem zmęczony. = I am tired.
• Ja jestem zmęczony, nie on. = I’m tired, not him.

Yes. Zmęczony agrees with the person’s gender and number.

For a man:

• Jestem zmęczony.

For a woman:

• Jestem zmęczona.

For a mixed group or a group of men:

• Jesteśmy zmęczeni.

For a group of women:

• Jesteśmy zmęczone.

So the form changes because Polish adjectives must agree with the noun or implied subject.

Oglądam is the 1st person singular present tense form of oglądać.

Conjugation:

• ja oglądam = I watch
• ty oglądasz = you watch
• on/ona ogląda = he/she watches

In this sentence, oglądam works well because the sentence describes something habitual or general: when I’m tired, I watch a film at home.

Also, oglądać is imperfective, which is often used for repeated or ongoing actions.

Because the sentence describes a habit or repeated situation, not one completed event.

• oglądać = imperfective, good for habits and ongoing actions
• a perfective counterpart like obejrzeć would suggest completing the film

So:

• Kiedy jestem zmęczony, oglądam film w domu.
  = a usual pattern / habit

If you said something with a perfective form, it would sound more like a single completed action in a specific situation.

Because film is the direct object of oglądam, and for a masculine inanimate noun in the singular, the accusative often looks the same as the nominative.

So:

• nominative: film
• accusative: film

That is why you get:

• Oglądam film. = I watch a film.

If the noun were masculine animate, the accusative would usually change differently.

Because w meaning in/at takes the locative case when it describes location.

• dom = house/home
• locative singular: domu

So:

• w domu = in the house / at home

This is very common in Polish, and w domu is the normal phrase for at home.

Polish does not have articles like English a/an and the.

So film can mean:

• a film
• the film

The exact meaning depends on context.

That is normal in Polish, and learners often need time to get used to the fact that definiteness is not marked with separate words.

Yes, Polish word order is more flexible than English, although some orders sound more natural than others depending on emphasis.

The given sentence:

• Kiedy jestem zmęczony, oglądam film w domu.

You could also say:

• Oglądam film w domu, kiedy jestem zmęczony.

Both are understandable. The original version sounds very natural because it starts with the condition or situation: when I’m tired.

Polish often moves parts around for emphasis, rhythm, or style.

In this kind of sentence, it can feel like whenever in English, because the sentence describes a repeated situation.

• Kiedy jestem zmęczony, oglądam film w domu.

This is not just one specific moment. It suggests a general pattern:

• When/Whenever I’m tired, I watch a film at home.

So kiedy literally means when, but in context it often carries that whenever sense.

A rough English-friendly guide:

• Kiedy ≈ KYEH-dih
• jestem ≈ YES-tem
• zmęczony ≈ zmeh-CHO-nih
• oglądam ≈ oh-GLON-dam
• film ≈ feelm
• w domu ≈ v DOH-moo

A few useful notes:

• ę is a nasal vowel, but before some consonants it may sound closer to em/en in practice.
• ą in oglądam is also nasal.
• w in Polish is pronounced like English v.
• Stress in Polish usually falls on the second-to-last syllable:
  • KIE-dy
  • JES-tem
  • zmę-CZO-ny
  • o-GLĄ-dam

Yes. W domu is just one location phrase. You can replace it with other places, as long as you use the correct case.

Examples:

• w kinie = at the cinema
• w łóżku = in bed
• w salonie = in the living room

So you can build similar sentences like:

• Kiedy jestem zmęczony, oglądam film w łóżku.

The grammar pattern stays the same.