Learn Hardcore Croatian: Moj prijatelj putnik piše blog o svojim izletima kako bi pomogao drugim putnicima. - My friend the traveler writes a blog about his trips so that he can help other travelers.

Prijatelj and putnik are both nouns here. Putnik is in apposition to prijatelj, so the phrase literally means “my friend, (who is a) traveler” or “my friend the traveler”.

Moj prijatelj putnik = my friend who is a traveler (friend + role/identity)
moj putujući prijatelj = my travelling friend (friend with the property of travelling)

So putnik tells you what kind of friend he is, but as a noun, not an adjective. Both versions are grammatically possible, but the original emphasizes his identity as a traveler, not just the fact that he happens to be travelling right now.

Could I also say Moj prijatelj je putnik piše blog… instead of Moj prijatelj putnik piše blog…?

No, not in one single clause like that.

Moj prijatelj je putnik. = My friend is a traveler. (full sentence)
Moj prijatelj putnik piše blog… = My friend (who is a traveler) writes a blog… (single clause)

If you want to use je, you need to split it into two clauses:

Moj prijatelj je putnik i piše blog…
My friend is a traveler and (he) writes a blog…

In the original sentence, putnik directly modifies prijatelj as a noun in apposition, so je is not used.

Is there supposed to be a comma: Moj prijatelj, putnik, piše blog…?

Both are possible, but they are slightly different in nuance:

Moj prijatelj putnik piše blog…
– more like “my friend who is a traveler writes a blog…”
– putnik is identifying which friend.
Moj prijatelj, putnik, piše blog…
– more like “my friend, a traveler, writes a blog…”
– putnik is extra information about the friend, not needed to identify him.

In many everyday contexts, the version without commas is natural here, because putnik helps identify the specific friend you have in mind.

What exactly does putnik mean? Is it more like traveler or passenger?

Putnik can mean both, depending on context:

traveler in a general sense (someone who travels a lot, loves trips)
passenger (on a bus, train, plane, etc.)

In this sentence, because he piše blog o svojim izletima (writes a blog about his trips), putnik is naturally understood as traveler rather than passenger.

Why is it piše blog, not something like napisao je blog?

Piše is the present tense of the imperfective verb pisati (to write), and it emphasizes an ongoing or habitual action:

Moj prijatelj putnik piše blog…
= My friend (who is a traveler) writes / is writing a blog…
– suggests it’s a regular activity (he runs a blog).

Napisao je blog (he wrote a blog) would describe a completed action in the past, like finishing one blog post or one specific blog project. That would not match the idea that he regularly writes a blog.

Why is it o svojim izletima and not o svoje izlete or some other case?

The preposition o (about) in Croatian is followed by the locative case:

o + locative → o svojim izletima

The noun izlet (trip, excursion) in the plural locative is:

nominative plural: izleti
locative plural: izletima

The endings -ima here mark dative / locative / instrumental plural for masculine nouns like izlet. So izletima is the correct locative form after o.

Why is it svojim izletima instead of njegovim izletima for his trips?

Croatian uses svoj as a reflexive possessive pronoun when the possessor is the subject of the clause.

Subject: Moj prijatelj putnik
Possessor of the trips: the same friend
So we use svojim izletima = his own trips

Compare:

Moj prijatelj putnik piše blog o svojim izletima.
= My friend the traveler writes a blog about his (own) trips.
Moj prijatelj putnik piše blog o njegovim izletima.
This suggests he writes about someone else’s trips (some other male person), not about his own.

So svojim is the natural and correct choice here.

What form is svojim exactly, and why that ending?

Svojim is the dative/locative/instrumental plural form of svoj.

It agrees with izletima in:

number: plural
gender: masculine (izlet)
case: locative (required by o)

Pattern:

nominative plural: svoji izleti (my own trips)
locative plural: o svojim izletima (about my own trips)

The matching endings -im (svojim) + -ima (izletima) show that both words are in the same case, number, and gender.

What is the nuance of izleti here? Could we also say putovanja?

Both are possible, but they’re not identical:

izlet(i)
– trip, excursion, often shorter, possibly a day trip, outing, hike, weekend away, etc.
putovanje(a)
– journey / travel, often broader or longer trips, can be international or more substantial travel.

So:

piše blog o svojim izletima
– suggests smaller, maybe more casual or frequent trips (weekend getaways, excursions).
piše blog o svojim putovanjima
– suggests more general or possibly longer travels.

The sentence as given focuses more on the idea of excursions/trips rather than big journeys.

What does kako bi pomogao mean, and why use this construction?

Kako bi pomogao introduces a purpose clause: in order to help.

kako here = so that / in order that
bi + pomogao = conditional form of pomoći (to help)

So kako bi pomogao drugim putnicima =
“so that he could help other travelers” / “in order to help other travelers”.

This structure is common in more careful or written Croatian for expressing purpose:

Piše blog kako bi pomogao…
= He writes a blog in order to help…

You can also often hear da bi pomogao, which is very similar, or simpler da pomogne, but kako bi sounds slightly more formal or literary.

Why is it pomogao, not pomaže, after bi?

After bi, Croatian normally uses a past participle form to create the conditional:

pomogao – masculine singular past participle of pomoći
bi pomogao – he would help / he could help (conditional)

So:

piše blog kako bi pomogao…
– literally: he writes a blog so that he *would help other travelers
– functionally: *in order to help other travelers

Using pomaže (helps) after bi would be ungrammatical; bi requires the participle (pomogao, pomogla, pomogli, etc., depending on gender and number).

Why is pomogao masculine? Does it agree with something?

Yes. Pomogao agrees with the subject moj prijatelj putnik, which is masculine singular.

Croatian conditional and past tense participles agree with the subject in:

gender: masculine / feminine / neuter
number: singular / plural

So:

Moj prijatelj putnik piše blog kako bi pomogao…
– prijatelj = masculine singular → pomogao

If the subject were feminine:

Moja prijateljica putnica piše blog kako bi pomogla drugim putnicima.
– prijateljica = feminine singular → pomogla

Why is drugim putnicima in the dative case?

The verb pomoći (to help) takes the dative case for the person being helped:

pomoći kome? – to help whom? → dative

Putnik (traveler) declension in plural:

nominative: putnici (travelers)
dative: putnicima (to/for travelers)

So:

drugim putnicima
– drugim = dative plural of drugi (other)
– putnicima = dative plural of putnik

Together: drugim putnicima = to other travelers, matching the verb pomogao (helped / would help someone).