Šta se desilo?

In this sentence, se is part of the verb desiti se, which means to happen.

So se is not being translated as itself in normal English. This is one of those Serbian verbs that you should learn together with se as a single dictionary item:

• desiti se = to happen
• nadati se = to hope
• smejati se = to laugh

So Šta se desilo? should be understood as a whole, not word-for-word as What itself happened?

Desilo is the past form of desiti se.

More precisely, it is the past participle form used to make the Serbian past tense. Serbian often uses this type of past form where English would simply use happened.

So:

• desiti se = to happen
• desilo se = happened

Because the verb is perfective, it refers to a completed event: something that happened as a whole.

Because šta is grammatically treated as neuter singular, and the past participle agrees with it.

That is why you get:

• šta ... desilo
• not šta ... desio
• not šta ... desila

This kind of agreement is very common in Serbian.

Compare with nouns of different genders:

• Udes se desio. = The accident happened.
  (udes is masculine)
• Nesreća se desila. = The accident/misfortune happened.
  (nesreća is feminine)

But with šta, Serbian uses the neuter form, so desilo is correct.

That is a very common learner question.

Yes, Serbian past tense often uses forms of biti such as je, su, sam, and so on. But with many verbs that use se, especially in the 3rd person singular, the auxiliary je is normally left out.

So the natural form is:

• Šta se desilo?

not:

• Šta se je desilo?

You will see the same pattern in many other examples:

• On se vratio. = He returned.
• Ona se rodila u Beogradu. = She was born in Belgrade.
• To se dogodilo juče. = That happened yesterday.

So even though learners often expect je, its absence here is normal.

Because se is a clitic. Clitics in Serbian usually go in the second position in the clause.

In this question, šta comes first, so se goes right after it:

• Šta se desilo?

This is why se is not placed at the very end.

You can think of it like this:

• first important word: šta
• clitic in second position: se
• rest of the verb phrase: desilo

This second-position behavior is one of the most important word-order patterns in Serbian.

Yes, in some varieties and regions, što can also mean what.

However, for a learner of Serbian, šta is the safest everyday choice in this sentence:

• Šta se desilo?

You may hear:

• Što se desilo?

but šta is the more typical default in standard Serbian conversation.

Yes, they are very close in meaning.

Both mean What happened?

The verbs are:

• desiti se = to happen
• dogoditi se = to happen

In everyday speech, Šta se desilo? is extremely common.
Šta se dogodilo? is also correct and natural, but can sound slightly more formal or a little less conversational to some speakers.

So both are good, but Šta se desilo? is a great everyday phrase to learn.

Because desiti se is perfective, and it asks about a completed event: What happened?

By contrast, dešavati se is imperfective and is used for ongoing, repeated, or habitual action.

Compare:

• Šta se desilo? = What happened?
• Šta se dešava? = What is happening?
• Šta se dešavalo? = What was happening? / What used to happen?

So if you are asking about one finished event, desilo se is the right choice.

A simple approximation is:

• Šta ≈ shta
• se ≈ seh
• desilo ≈ deh-see-loh

A few pronunciation notes:

• Š sounds like sh in ship
• a is like the a in father
• e is a short clear e, like in met
• i is like ee in see
• o is a clear short o

So the whole sentence sounds roughly like:

SHTA seh DEH-see-loh?

It is basically neutral and very common.

You can use Šta se desilo? in everyday conversation, when checking on someone, or when reacting to news. It does not sound especially slangy or especially formal.

So it is a very useful all-purpose phrase for learners.