Susjeda se često žali na buku iz hodnika, ali se danas nije žalila jer je zgrada bila vrlo tiha.

Susjeda is the feminine singular noun meaning female neighbor. In this sentence it is in the nominative singular because it is the subject of the verb.

• susjed = male neighbor
• susjeda = female neighbor

So the sentence is specifically about a woman.

Croatian has no articles, so it does not use words like the or a/an.

That means:

• susjeda can mean a neighbor or the neighbor
• zgrada can mean a building or the building

The exact meaning comes from context. In this sentence, English would most naturally say the neighbor and the building.

Because žaliti se is the normal Croatian verb meaning to complain. The se is part of the verb expression.

So:

• žaliti se = to complain
• žaliti without se usually means to pity, to feel sorry for, or to regret

For example:

• Žali se na buku. = She is complaining about the noise.
• Žalim te. = I feel sorry for you.
• Žalim zbog toga. = I regret that.

They are different tense forms of the same verb.

• žali = present tense, 3rd person singular
  
  • she complains / is complaining
• žalila = past participle, feminine singular, used to form the past tense
  
  • she complained

The ending -la in žalila shows that the subject is feminine.

The first clause describes a habitual action:

• Susjeda se često žali... = The neighbor often complains...

The adverb često shows that this is something that happens regularly, so Croatian uses the present tense.

The second clause refers to a specific situation today:

• ali se danas nije žalila... = but today she did not complain...

That is why it switches to the past tense.

In Croatian, the past tense is made with:

• a form of biti = to be
• plus the past participle

So:

• je žalila = she complained
• nije žalila = she did not complain

Here nije is the negative form of je.

So Croatian does not form this the same way English does with did not. Instead, it uses the negative auxiliary plus the participle.

Croatian often drops subject pronouns when the subject is already clear.

Once susjeda has been introduced, there is usually no need to add ona.

So Croatian naturally says:

• ali se danas nije žalila

rather than:

• ali ona se danas nije žalila

Adding ona would usually give extra emphasis, contrast, or stress.

Because the expression is:

žaliti se na + accusative

So after na in this meaning, buka changes into the accusative case:

• buka = nominative
• buku = accusative

That is why we get:

• žali se na buku = complains about the noise

Because the preposition iz normally takes the genitive case.

The noun changes like this:

• hodnik = nominative
• hodnika = genitive

So:

• iz hodnika = from the hallway / from the corridor

Because they agree with zgrada, which is a feminine singular noun.

So Croatian uses:

• zgrada je bila vrlo tiha

Here:

• bila = past form agreeing with feminine singular subject
• tiha = adjective agreeing with feminine singular subject

Compare:

• bio tih = masculine singular
• bila tiha = feminine singular
• bilo tiho = neuter singular

Also, vrlo means very and does not change form.

Croatian word order is fairly flexible, but short unstressed words like se usually appear near the beginning of the clause.

That is why se comes early here:

• ali se danas nije žalila

This sounds natural in Croatian. You may also hear:

• ali danas se nije žalila

The meaning is basically the same, but the emphasis and rhythm are slightly different.