Gdy wracam do domu mokra od deszczu, zostawiam płaszcz na wieszaku.

Polish often drops subject pronouns when the verb ending already shows who the subject is.

• wracam = I return / I am returning
• zostawiam = I leave / I am leaving

So ja is not needed. You could say Gdy ja wracam..., but it usually sounds unnecessary unless you want emphasis, contrast, or clarification.

Here gdy means when.

In many everyday contexts, gdy and kiedy can both mean when:

• Gdy wracam do domu...
• Kiedy wracam do domu...

Both are natural.

A useful rough guide:

• gdy often sounds a bit more written, neutral, or slightly formal
• kiedy is very common in everyday speech

In this sentence, either works well.

Because Polish often uses the present tense for habitual or repeated actions.

So this sentence means something like:

• Whenever I come home wet from the rain, I leave my coat on the hanger
• or When I come home wet from the rain, I leave my coat on the hanger

Both wracam and zostawiam are present tense, and together they describe a regular pattern, not necessarily what is happening right this second.

Because the preposition do means to and it requires the genitive case.

• dom = house / home
• do domu = to home / homeward

So:

• wracam do domu = I’m returning home

This is a very common pattern:

• iść do sklepu = to go to the store
• jechać do pracy = to go to work
• wracać do domu = to return home

Because mokra agrees with the speaker, and it shows that the speaker is female.

The adjective refers to the implied I:

• mokra = feminine singular
• mokry = masculine singular

So:

• a woman says Gdy wracam do domu mokra...
• a man says Gdy wracam do domu mokry...

This is a very important clue in Polish: adjectives often reveal the gender of the speaker even when the pronoun ja is omitted.

It describes the subject I. It means wet from the rain.

So the structure is:

• Gdy wracam do domu = when I come home
• mokra od deszczu = wet from the rain
• zostawiam płaszcz na wieszaku = I leave my coat on the hanger

In natural English, we often place this description a little differently, but in Polish it is normal for this adjective phrase to appear like this and describe the subject.

Because od here means something like from or because of, and it takes the genitive case.

• deszcz = rain
• od deszczu = from the rain

So mokra od deszczu literally means wet from the rain.

This pattern is common:

• zmęczony od pracy = tired from work
• brudny od błota = dirty from mud

Because after od, Polish uses the genitive case.

The base form is:

• deszcz = rain

After od it becomes:

• od deszczu = from the rain

So this is just case change caused by the preposition.

Płaszcz is in the accusative case because it is the direct object of zostawiam.

• płaszcz = coat
• zostawiam płaszcz = I leave the coat

For many masculine inanimate nouns, the accusative singular looks the same as the nominative singular, so you do not see a form change here.

That is why:

• nominative: płaszcz
• accusative: płaszcz

same form, different function

It means on the hanger or on the coat rack, depending on context.

• wieszak can mean a clothes hanger
• it can also mean a wall hanger, hook, or coat rack depending on the situation

So zostawiam płaszcz na wieszaku means that the coat is left hanging there.

Because na can take different cases depending on meaning.

Here it expresses location, so it takes the locative case:

• na wieszaku = on the hanger / on the rack

If it expressed movement onto something, you would often get the accusative instead:

• położyć coś na stół = to put something onto the table

In this sentence, the coat ends up being located there, so na wieszaku is the natural form.

The most direct translation is I leave.

In context, natural English could also be:

• I leave my coat on the hanger
• I hang my coat on the hanger
• sometimes even I put my coat on the hanger

But the Polish verb zostawiać / zostawić basically means to leave. It focuses on leaving something somewhere, not specifically on the act of hanging it up.

Because the sentence describes a repeated habit, I leave is usually the best match.

Because the sentence describes a habitual, repeated situation.

• wracać = imperfective to be returning / to return habitually
• zostawiać = imperfective to be leaving / to leave habitually

Imperfective verbs are very common when talking about routines or repeated actions.

If you wanted a one-time completed event, Polish would usually use a different structure, often with perfective verbs, for example in the future:

• Gdy wrócę do domu, zostawię płaszcz na wieszaku.
• When I get home, I’ll leave the coat on the hanger.

So in your original sentence, the imperfective aspect helps create a whenever this happens, this is what I do meaning.

It describes the speaker.

That is clear because:

• domu is masculine and in the genitive, so mokra cannot agree with it
• płaszcz is masculine, so mokra cannot agree with that either
• mokra is feminine singular, matching the implied ja if the speaker is female

So the sentence means that I am wet from the rain, not the home or the coat.

Because Gdy wracam do domu mokra od deszczu is a subordinate clause placed before the main clause.

So Polish uses a comma before the main clause:

• Gdy wracam do domu mokra od deszczu, zostawiam płaszcz na wieszaku.

This is similar to English punctuation in sentences like:

• When I get home, I leave my coat on the hanger.

Yes, Polish word order is flexible, though not completely free. The original sentence is natural and neutral.

You could also hear variations like:

• Gdy wracam do domu mokra od deszczu, płaszcz zostawiam na wieszaku.
• Płaszcz zostawiam na wieszaku, gdy wracam do domu mokra od deszczu.

These shifts change emphasis a little:

• putting płaszcz earlier can emphasize the coat
• putting the main clause first can sound more marked or stylistically different

For a learner, the original order is a very good model.

Only the adjective showing the speaker’s gender:

• Gdy wracam do domu mokry od deszczu, zostawiam płaszcz na wieszaku.

So:

• mokra = female speaker
• mokry = male speaker

The verbs stay the same in the present tense: wracam, zostawiam.

Grammatically, yes, dom means house/home, and do domu literally means to the house/home.

But in this sentence, English naturally uses home:

• wracam do domu = I’m coming home / I return home

That is the most idiomatic translation here.