Izvinjavam se zbog kašnjenja.

Because izvinjavati se / izviniti se is a reflexive verb in Serbian, and it normally comes with se.

• izvinjavati se = to apologize
• izviniti se = to apologize

So Izvinjavam se literally works like I am apologizing or I apologize.

Without se, the verb would not sound natural here. In practice, when you want to say I apologize, you should use izvinjavam se or izvinite / izvini depending on the situation.

In Serbian, just like in English, the present tense can be used for a speech act happening right now.

So Izvinjavam se means I am apologizing now / I apologize.

The lateness may have already happened, but the apology is happening at the moment of speaking. That is why the present tense is perfectly natural.

The basic dictionary form is usually given as either:

• izvinjavati se — imperfective
• izviniti se — perfective

In your sentence, izvinjavam se is the 1st person singular present of izvinjavati se:

• ja se izvinjavam = I apologize

You will often see Serbian verbs in aspect pairs:

• izvinjavati se = imperfective
• izviniti se = perfective

Very roughly:

• imperfective focuses on the process, repetition, or ongoing action
• perfective focuses on a completed act

In everyday apology formulas, izvinjavam se is very common and natural.

Zbog means because of, due to, or on account of.

So:

• zbog kašnjenja = because of the delay / for being late

It introduces the reason for the apology.

This is a very common pattern in Serbian:

• Izvinjavam se zbog greške. = I apologize for the mistake.
• Izvinjavam se zbog neprijatnosti. = I apologize for the inconvenience.
• Izvinjavam se zbog kašnjenja. = I apologize for the delay / for being late.

Because zbog requires the genitive case.

The noun is:

• kašnjenje = delay, lateness

But after zbog, it changes to the genitive singular:

• zbog kašnjenja

So the structure is:

• zbog + genitive

More examples:

• zbog problema = because of the problem
• zbog gužve = because of the traffic / crowding
• zbog vremena = because of the weather / time, depending on context

It can correspond to either delay or lateness, depending on context.

In Izvinjavam se zbog kašnjenja, English might translate it as:

• I apologize for the delay.
• I’m sorry for being late.

Both are possible. Serbian kašnjenje is a noun meaning delay, being late, or lateness.

So if a person arrives late, or a message/reply/service is delayed, this phrase still works.

Yes, it sounds fairly formal or neutral-polite.

It is very appropriate in:

• emails
• customer service
• professional situations
• public announcements

For casual everyday speech, people also commonly say:

• Izvini što kasnim. = Sorry I’m late.
• Izvini zbog kašnjenja. = Sorry for the delay.
• Oprosti zbog kašnjenja. = Sorry for the delay. (common in some regions)

So your sentence is correct and natural, especially in more polite or written contexts.

Yes, but the structure is a bit different.

• Izvinjavam se zbog kašnjenja. = I apologize for the delay.
• Izvinite zbog kašnjenja. = Excuse me / Sorry for the delay.

Izvinite is the formal/plural imperative form, but in real usage it often functions as a polite apology formula, similar to sorry or excuse me.

So both are natural, but:

• Izvinjavam se zbog kašnjenja sounds a little more complete and formal
• Izvinite zbog kašnjenja sounds shorter and also very common

Yes, Serbian word order is fairly flexible, though some versions are more natural than others.

The standard order here is:

• Izvinjavam se zbog kašnjenja.

You could also hear or see:

• Zbog kašnjenja se izvinjavam.

That version puts more emphasis on because of the delay, but it sounds more marked or stylistically special. For a learner, the safest and most natural choice is:

• Izvinjavam se zbog kašnjenja.

A simple pronunciation guide would be:

• Izvinjavam se zbog kašnjenja
• roughly: ee-zvee-NYAH-vam seh zbohg kash-NYE-nya

A few useful notes:

• j in Serbian is like English y in yes
• nj is like the ny sound in canyon
• ž sounds like the s in measure
• zbog is pronounced with a clear z+b cluster at the start

So kašnjenja has that soft nj sound: kaš-nje-nja.

No. It is broader than that.

You can use Izvinjavam se zbog kašnjenja in many situations, for example:

• arriving late to a meeting
• replying late to a message
• sending something after the deadline
• a train, bus, or service being delayed
• a business apologizing to customers

So kašnjenje can refer to both personal lateness and general delay.