Learn Hardcore Polish: On zwykle wychodzi z domu rano. - He usually leaves the house in the morning.

emphasize who you’re talking about (e.g. in contrast: On wychodzi, a ona zostaje – He leaves, and she stays), or
make it very clear at the beginning of a conversation who the subject is.

In many neutral contexts, leaving out On is more natural: Zwykle wychodzi z domu rano.

Why is it wychodzi and not wychodzić or something else?

Wychodzi is the 3rd person singular present tense form of the verb wychodzić (to go out, to leave):

infinitive: wychodzić – to leave / to go out
ja (I) – wychodzę
ty (you, sg.) – wychodzisz
on/ona/ono (he/she/it) – wychodzi
my (we) – wychodzimy
wy (you, pl.) – wychodzicie
oni/one (they) – wychodzą

You use the present tense (here: wychodzi) to talk about habitual actions, just like English simple present in He usually leaves the house in the morning.

The infinitive wychodzić is only used where English uses to leave as an infinitive (e.g. after another verb, in dictionaries, etc.), not as the main verb of a finite sentence.

What’s the difference between wychodzić and wyjść? They both seem to mean “to leave”.

Polish verbs come in aspective pairs:

wychodzić – to be leaving / to leave habitually
- imperfective aspect
- used for repeated, ongoing, or not‑completed actions
wyjść – to leave (once, as a complete event)
- perfective aspect
- used for a single, completed action or the result

In your sentence (a habitual action):

On zwykle wychodzi z domu rano. – He usually leaves the house in the morning.

If you talk about one specific time, you’d normally use wyjść (in past or future):

Wyszedł z domu rano. – He left the house in the morning (this morning / one specific time).
Wyjdzie z domu rano. – He will leave the house in the morning (once).

Why is it z domu and not just z dom or z domem? What case is that?

Domu is the genitive singular form of dom (house).

The preposition z (from, out of) in the sense of movement from the inside of something requires the genitive case:

z domu – from (the) house
z pracy – from work
z kina – from the cinema
z autobusu – from the bus

So the pattern is:

z + [noun in genitive] → “from / out of [noun]”

Z domem would be with the house (instrumental case), so it would be wrong here.

What exactly does z mean here? How is it different from od or z in other contexts?

Here z means “from / out of” and implies movement from the inside of a place:

wychodzi z domu – he goes out of the house
wraca z pracy – he returns from work

Rough comparison:

z – from the inside / from a location (z domu, z biura, z kina)
od – from a person or from the vicinity of something (od kolegi – from a friend; od lekarza – from the doctor; od domu – from near the house / away from the house, not necessarily from inside)

So wychodzi z domu is “he goes out of the house” (literally), which is exactly what you want.

Why do we say rano without a preposition? Why not w rano like “in the morning”?

Rano is an adverb of time, and Polish often uses bare adverbs where English uses a preposition + noun phrase:

rano – in the morning
wieczorem – in the evening
popołudniu – in the afternoon
w nocy – at night (here w happens to be used)

So the standard, natural expression is simply:

On zwykle wychodzi z domu rano. – He usually leaves the house in the morning.

You don’t say w rano in standard Polish.

Can I change the word order? For example: On rano zwykle wychodzi z domu or On wychodzi z domu zwykle rano?

Yes. Polish word order is flexible. All of these are grammatical, though they may have slightly different rhythms or emphasis:

On zwykle wychodzi z domu rano. – neutral, very natural.
On rano zwykle wychodzi z domu. – still natural; a tiny bit more focus on rano.
On zwykle rano wychodzi z domu. – also good; the two adverbs sit together.
On wychodzi z domu zwykle rano. – also correct; here the chunk zwykle rano comes as an afterthought or emphasis at the end.

For a learner, keeping [subject] [zwykle] [verb] [z domu] [rano] is a safe, natural default.

Where should other frequency adverbs go, like często (often) or czasami (sometimes)?

They behave like zwykle, and commonly go before the verb:

On często wychodzi z domu rano. – He often leaves the house in the morning.
On czasami wychodzi z domu rano. – He sometimes leaves the house in the morning.

You can also move them around similarly for nuance:

On rano często wychodzi z domu.
On wychodzi z domu często rano.

But the most neutral, learner‑friendly pattern is:

[On] + [frequency adverb] + [verb] + z domu + rano

How would I say “He is leaving the house now” as opposed to “He usually leaves the house in the morning”?

Habitual action (your original sentence):
- On zwykle wychodzi z domu rano.
  – He usually leaves the house in the morning.
- Verb: wychodzi (imperfective, present) used for habit/habitual.
Action happening right now:
Polish doesn’t have a separate continuous form like English is leaving. You still use the simple present, and add a time word like teraz (now):
- On teraz wychodzi z domu. – He is leaving the house now.
- On właśnie wychodzi z domu. – He is just now leaving the house / He’s leaving right now.

Same verb form wychodzi, but the adverb (e.g. teraz, właśnie) plus context tell you it’s happening now, not habitually.