Kad nastane nesporazum, pokušavamo mirno objasniti jedno drugome što smo mislili.

Nastane is the present form of the perfective verb nastati. After kad, Croatian often uses a perfective present to talk about something that happens whenever that situation comes up: when a misunderstanding arises.

By contrast:

• nastaje is imperfective and suggests a process or ongoing emergence
• nastao je is past tense and refers to a specific past event

So kad nastane nesporazum is a normal way to say when a misunderstanding arises/comes up.

Croatian usually does not need an explicit subject pronoun if the verb ending already shows who the subject is. Here pokušavamo already means we try, and smo mislili also shows first person plural.

You could add mi for emphasis, but it is not necessary.

Because Croatian commonly uses pokušavati/pokušati + infinitive to mean to try to do something. So pokušavamo objasniti means we try to explain.

Unlike English, Croatian does not need a separate word like to before the second verb.

Because mirno is an adverb here, meaning calmly. It describes how the explaining is done.

Compare:

• miran čovjek = a calm man → adjective
• govoriti mirno = to speak calmly → adverb

So mirno objasniti means to explain calmly.

It means to each other or to one another. This is a reciprocal expression, literally something like one to the other.

It is in the dative here because objasniti often follows the pattern objasniti nešto nekome = to explain something to someone.

So:

• objasniti što smo mislili = explain what we meant
• objasniti jedno drugome što smo mislili = explain to each other what we meant

For larger groups, you will also often see jedni drugima. Jedno drugome is especially common when two people are involved.

Here što means what. It introduces the embedded clause that tells us the content of the explanation: what we meant or what we were thinking.

So the structure is:

• objasniti = explain
• što smo mislili = what we meant / what we had in mind

Smo is a clitic auxiliary used to form the past tense. Croatian clitics usually go in the second position in their clause.

So in što smo mislili, smo comes right after što. That word order is normal Croatian clitic placement.

Because mislili is the masculine plural past participle, and in Croatian that form is also the default plural when the group is mixed or unspecified.

So with mi = we, mislili is the normal general form. If the speakers were all female, it would be mislile.

Yes, literally it comes from misliti = to think. But in Croatian, misliti can also mean to have in mind, to intend, or to mean, depending on context.

In a sentence about resolving a misunderstanding, što smo mislili is very naturally understood as what we meant.

This is a question of aspect.

• objasniti is perfective: it presents the explanation as a complete act or successful result
• objašnjavati is imperfective: it focuses more on the process, duration, or repetition of explaining

Here objasniti fits well because the idea is that, when a misunderstanding happens, we try to explain clearly/completely what we meant.

Because Kad nastane nesporazum is a subordinate clause placed before the main clause. In Croatian, when a kad clause comes first, it is normally separated from the main clause with a comma.

So: Kad nastane nesporazum, pokušavamo... is standard punctuation.