Learn Hardcore Croatian: On često radi kasno, ali njegov posao je gotov prije ponoći, jer mu je važan. - He often works late, but his work is finished before midnight because it is important to him.

Yes. Croatian is a pro‑drop language, so On can be omitted when the subject is clear from context. You can say: Često radi kasno, ali njegov posao je gotov prije ponoći, jer mu je važan. Using On just adds slight emphasis or clarity.

Why is it njegov posao and not svoj posao?

Use svoj when the possessor is also the grammatical subject of that clause. Here, the subject of the second clause is posao (the job), not the person. Since the possessor isn’t the subject of this clause, you must use njegov. Compare:

Correct: On je završio svoj posao. (He finished his own job. Subject = On.)
Correct: Njegov posao je gotov. (His job is finished. Subject = posao.)
Incorrect here: Svoj posao je gotov. (Would mean the job’s own job.)

Why is the word order jer mu je važan and not jer je mu važan?

Short unstressed pronouns and auxiliaries (clitics) like mu and je must sit near the start of the clause (the “second position”). After the conjunction jer, the clitics come immediately, and within the clitic cluster the dative pronoun mu precedes je: jer mu je.... So jer mu je is natural; jer je mu is not.

What does mu mean here, and why that form?

Mu is the short dative form of njemu (to him). With adjectives like važan/važno, Croatian uses the dative to express “to someone”: Važno mi je, Jasno ti je, Hladno mu je. Here: jer mu je važan = “because it is important to him.”

Why is it važan and not važno?

The adjective agrees with the subject it describes. The implied subject is posao (masculine singular), so you need masculine singular važan. If the subject were to (it), you’d use neuter: jer mu je to važno.

Why is it gotov and not gotova/gotovo?

Same agreement rule: gotov (masc. sg.) agrees with posao (masc. sg.). With a feminine subject (e.g., zadaća) you’d say Zadaća je gotova; with a neuter subject (e.g., pismo) you’d say Pismo je gotovo.

Is there a difference between gotov and završen?

Both mean “finished,” but:

gotov is very common and colloquial.
završen can sound a bit more formal or process‑oriented (“completed”). Here both are fine: Njegov posao je gotov/završen. You may also see dovršen (“brought to completion”), which is less common.

What case is used after prije, and why is it ponoći?

Prije takes the genitive. Ponoć (midnight) in the genitive singular is ponoći. Other time prepositions that take genitive: poslije/iza/nakon. Examples:

prije ponoći (before midnight)
poslije ponoći (after midnight)

Could I say do ponoći instead of prije ponoći?

Yes, but the nuance differs:

prije ponoći = sometime before midnight (unspecified).
do ponoći = by midnight (deadline/upper limit). So choose based on meaning.

What’s the difference between radi kasno and radi do kasno?

radi kasno = he works at late hours (works late).
radi do kasno = he works until late (works late into the night). The second highlights the stretch of time up to a late hour.

Can I move često elsewhere? For example, On radi često kasno?

Best placement is before the verb or right after the subject: On često radi kasno or Često radi kasno. On radi često kasno is understandable but less natural. Adverbs like često, uvijek, rijetko usually precede the verb.

Why are there commas before ali and jer?

ali (but) joins two independent clauses → comma before it.
jer (because) introduces a subordinate clause → comma before it. So: ..., ali ... , jer ... is standard punctuation.

Could mu and njemu both work here?

Grammatically yes, but they differ in emphasis and rhythm:

mu (clitic, unstressed) is the normal choice: ..., jer mu je važan.
njemu (stressed) adds contrast or emphasis: ..., jer je njemu važan. (implies “to him, specifically/especially”). Use njemu when you want to stress the person.

Is there any ambiguity about who mu refers to?

Potentially, yes. mu could refer to the same person as On or to another previously mentioned male. Context resolves it. If you need clarity, use a name or a stressed pronoun: jer je njemu (Ivanu) važan.

What’s the difference between jer, zato što, pošto, and budući da?

All can mean “because,” but:

jer = neutral, very common.
zato što = “because” with a slight emphasis on the reason; often interchangeable with jer.
pošto = in Croatian often means “since/because” in speech, but it also means “after” in other contexts; can be avoided in careful writing to prevent ambiguity.
budući da = “since/as,” more formal or explanatory.

Could I say jer mu je to važno instead?

Yes. That makes to (it) the explicit subject and uses neuter važno: ..., jer mu je to važno. Your original ties the adjective directly to posao (važan).

Why is the present tense radi used to mean a habitual action?

Croatian present simple covers habitual actions just like English simple present: On često radi kasno = “He often works late (as a habit).”

Is posao the right word here, or should it be rad?

posao = a job, work assignment, employment (countable task/job).
rad = work as an activity/effort (uncountable/abstract), or a written paper. Here, posao is correct: Njegov posao je gotov. Saying Njegov rad je gotov would usually mean “his paper/work (as a product) is finished.”

Any pronunciation or spelling tips for često, ponoći, and važan?

često: the first consonant is č (like ch in “chop,” but harder), not ć.
ponoći: genitive of ponoć; ć is a softer “ch” sound than č.
važan: ž is like the s in “measure.” The final -an is unstressed.

Is je required in posao je gotov?

Yes, in a full sentence you need the copula je: Posao je gotov. You can drop it only in very telegraphic style (headlines, notes), which isn’t the case here.