Learn Hardcore Croatian: Njeno objašnjenje zašto kasni bilo je komplicirano i puno detalja. - Her explanation of why she is late was complicated and full of details.

Njena is the feminine form and would be used with a feminine noun, e.g. njena knjiga (her book). With objašnjenje, you must use njeno/njezino.

What is the difference between njeno and njezino?

They mean the same thing: her.

njezino is the more standard, careful form.
njeno is a very common shorter form in everyday speech and writing.

Both are grammatically correct and both agree with neuter nouns like objašnjenje. In very formal writing you’ll see njezino more often.

What case is njeno objašnjenje in, and why?

Njeno objašnjenje is in the nominative case.

It’s the grammatical subject of the sentence – the thing that “was complicated and full of details”. In Croatian, the subject normally stands in the nominative, just as in this example.

How should I understand zašto kasni? Is something missing, like ona?

In Croatian, subject pronouns are usually dropped when the subject is clear from context. So:

(ona) kasni = (she) is late

In njezino objašnjenje zašto kasni, the implied subject of kasni is ona (the same “she” whose explanation it is). The language doesn’t need to repeat ona; native speakers automatically connect kasni with njeno.

Is zašto kasni a special type of clause?

Yes. Zašto kasni is an indirect question clause (a subordinate clause introduced by zašto = why).

Roughly: njezino objašnjenje [zašto kasni] = her explanation [of why she is late]. It functions as a complement of objašnjenje, just like in English explanation of why….

Why is the verb kasni in the present, when the main verb is in the past (bilo je)?

The tense in the subordinate clause is independent of the main verb’s tense.

bilo je describes the time of the explanation (in the past).
kasni describes the lateness relative to the moment being talked about (she is late now / at that moment).

You could also say njezino objašnjenje zašto je kasnila if you mean “her explanation of why she was late (on that one past occasion)”. With zašto kasni, the lateness is seen as present/ongoing in the situation being described.

Why is it bilo je and not just bilo or just je?

Croatian forms the past tense of most verbs with:

a past participle (bilo) + a short auxiliary form of biti (je).

So:

je = is (present tense)
bilo je = was (past)

You need both parts in the past tense here. Just bilo would be incomplete in standard language, and je alone would make it present (her explanation is complicated), which doesn’t match the intended meaning.

Could I also say Njeno objašnjenje zašto kasni je bilo komplicirano? Where does je go?

You can say njezino/njeno objašnjenje zašto kasni je bilo komplicirano i puno detalja, and it’s perfectly correct.

In neutral sentences, the clitic je usually goes into the second position in the clause, after the first stressed word or phrase. Both of these are acceptable:

Njeno objašnjenje zašto kasni je bilo komplicirano i puno detalja.
Njeno objašnjenje zašto kasni bilo je komplicirano i puno detalja.

The difference is very small; both sound natural. Word order here is more about rhythm and emphasis than strict rules.

Why is komplicirano in the neuter form?

Because it agrees with the subject objašnjenje, which is neuter:

objašnjenje → neuter singular
komplicirano → neuter singular form of the adjective kompliciran

Croatian adjectives used as a “description after to be” (a predicate adjective) agree in gender and number with the subject: objašnjenje je komplicirano, priča je komplicirana, plan je kompliciran.

Is komplicirano an adjective or an adverb here?

Formally, komplicirano can be both:

neuter singular adjective (agreeing with a neuter noun), or
the adverb form (“in a complicated way”).

In this sentence it’s best understood as a predicate adjective agreeing with objašnjenje: the explanation was complicated. The form happens to look identical to the adverb, but grammatically it’s functioning as an adjective.

What exactly is happening in i puno detalja? How does that connect to the verb?

The full idea is:

(bilo je) komplicirano i (bilo je) puno detalja

The second bilo je is simply left out because it’s the same verb and tense as in the first part. So:

bilo je komplicirano i puno detalja ≈ it was complicated and (it was) full of details / it had a lot of details.

Croatian often omits the repeated verb in such coordinated structures when the meaning is clear.

Why is it puno detalja and not puno detalji or puno detalje?

Because puno (a lot of, much/many) normally takes a genitive form after it:

puno detalja (genitive plural of detalj)
puno vremena
puno ljudi

So detalja is the genitive plural. Saying puno detalji or puno detalje would be wrong in standard Croatian.

Is puno here more like “many” or “full of”?

Literally, puno detalja means a lot of details / many details. In this sentence, though, it effectively describes the explanation as being full of details.

So:

literal: it was complicated and (there were) many details
natural reading in English: it was complicated and full of details

Could I replace puno with something else, like mnogo?

Yes. The most natural synonym here is mnogo:

…bilo je komplicirano i mnogo detalja.

Puno is more colloquial and very common; mnogo sounds a bit more formal or bookish, but both mean “a lot/many” and both take the genitive (mnogo detalja).

Are there more natural or alternative ways to say the whole sentence?

A few very natural variants would be:

Njezino objašnjenje zašto kasni bilo je jako komplicirano i puno detalja.
(adds jako = very)
Njezino objašnjenje zašto kasni bilo je prilično komplicirano i prepuno detalja.
(prepuno detalja = packed with details)
Njezino objašnjenje zašto kasni bilo je komplicirano i prepuno sitnih detalja.

All keep the same overall meaning; they just adjust tone and emphasis slightly.