Kad ne razumijem sugovornika, osjetim malo tuge, ali taj osjećaj brzo prođe.

Kad means when here.

Yes, you could also say kada. The difference is mostly stylistic:

• kad = more common in everyday speech
• kada = a bit fuller or more formal

So:

• Kad ne razumijem sugovornika...
• Kada ne razumijem sugovornika...

Both are correct.

Because both verbs are in the 1st person singular present tense: I understand / I feel.

• razumijem = I understand
• osjetim = I feel

Croatian verbs change their endings depending on the subject, much like in many European languages. Here the subject is understood as I, so no separate pronoun (ja) is needed.

Croatian often drops subject pronouns when the verb ending already shows who the subject is.

So instead of saying:

• Ja ne razumijem...
• Ja osjetim...

Croatian normally just says:

• Ne razumijem...
• Osjetim...

The -m ending already tells you it means I.

Because sugovornika is in the accusative singular, not the nominative.

The verb razumjeti takes a direct object: you understand someone or something. Here, sugovornik is that object.

Since sugovornik refers to a person and is a masculine animate noun, its accusative singular looks like the genitive singular:

• nominative: sugovornik = the interlocutor / conversation partner
• accusative: sugovornika = the interlocutor (as object)

So:

• Ne razumijem sugovornika = I don't understand the person I'm speaking with

Sugovornik means something like:

• interlocutor
• the person you are talking to
• conversation partner

It is a fairly neutral word. In everyday English, the person I’m talking to is often the most natural translation.

Because malo here means a little / a small amount of, and after that Croatian normally uses the genitive.

So:

• malo tuge = a little sadness
• literally: a little of sadness

This is different from mala tuga, which would mean small sadness, and that sounds unnatural here.

This pattern is very common:

• malo vode = a little water
• malo vremena = a little time
• malo sreće = a little happiness
• malo tuge = a little sadness

Tuge is the genitive singular of tuga (sadness).

As mentioned above, malo often requires the genitive, so:

• nominative: tuga
• genitive: tuge

That is why the sentence says malo tuge.

Yes, they are related.

• osjetim = I feel (verb form, from osjetiti)
• osjećaj = feeling (noun)

So in the sentence:

• osjetim malo tuge = I feel a little sadness
• taj osjećaj = that feeling

Even though the forms are not identical, they belong to the same word family.

Taj means that, and it agrees with osjećaj in gender, number, and case.

• osjećaj is masculine singular
• here it is the subject of prođe
• so it is in the nominative singular

That is why we get:

• taj osjećaj = that feeling

It refers back to the sadness just mentioned.

Prođe comes from the verb proći, which literally means to pass.

In this sentence, it means:

• passes
• goes away
• doesn’t last long

So:

• taj osjećaj brzo prođe = that feeling passes quickly

This is a very natural way in Croatian to talk about emotions or states that do not last.

Because proći is a very common verb for experiences, emotions, pain, and temporary states that pass.

For example:

• Bol je prošla. = The pain passed.
• Strah me brzo prođe. = The fear quickly passes.
• To će proći. = It will pass.

You could sometimes use nestati (disappear), but proći is often more idiomatic in this kind of sentence.

Yes. Croatian uses the present tense here to talk about a habitual or general situation:

• Kad ne razumijem sugovornika... = When I don’t understand the person I’m talking to...
• osjetim... = I feel...
• prođe = it passes...

This is very normal. English does the same in sentences like:

• When I don’t understand someone, I feel frustrated.

So the present tense here does not mean only right now; it can also mean whenever this happens.

Because Kad ne razumijem sugovornika is a subordinate clause introduced by kad.

Croatian normally separates that clause from the main clause with a comma:

• Kad ne razumijem sugovornika, osjetim malo tuge...

This is standard punctuation.

Yes, Croatian word order is fairly flexible, although some versions sound more natural than others.

The original sentence is very natural:

• Kad ne razumijem sugovornika, osjetim malo tuge, ali taj osjećaj brzo prođe.

You might also hear variations like:

• Kad ne razumijem sugovornika, malo tuge osjetim...
  This is grammatical, but less neutral and more marked.

• Ali taj osjećaj prođe brzo.
  Also possible, though brzo prođe sounds slightly more natural here.

So the given word order is a good, neutral choice.

Because Croatian does not have articles like English a/an/the.

That means nouns appear without articles, and context does the job.

For example:

• sugovornika can mean the interlocutor or simply an interlocutor, depending on context
• taj osjećaj is specific because taj already means that

English learners often look for articles in Croatian, but they simply are not part of the language.