Saya telat ke kantor gara-gara jalanan macet.

In Indonesian, you often do not need a verb like to be between the subject and an adjective or state.

So:

• Saya telat = I am late
• literally, it is more like I late

This is completely normal Indonesian grammar. The adjective/state word can act as the predicate by itself.

Telat means late. In this sentence, it means to be late.

Yes, it is very close in meaning to terlambat, but there is a difference in tone:

• telat = more casual, everyday speech
• terlambat = more neutral or formal

So:

• Saya telat ke kantor = casual, natural in conversation
• Saya terlambat ke kantor = also correct, slightly more formal

A learner will hear telat very often in daily Indonesian.

Ke is a preposition meaning to when talking about movement or destination.

So:

• ke kantor = to the office

Examples:

• Saya pergi ke kantor = I go to the office
• Dia datang ke rumah saya = He/She comes to my house

In your sentence, ke kantor shows the destination connected with being late: late to the office / late for work.

Indonesian does not usually use articles like a, an, or the.

So kantor can mean:

• office
• the office
• sometimes even an office

The exact meaning depends on context. In this sentence, ke kantor naturally means to the office or to work.

Gara-gara means because of, due to, or as a result of. It is commonly used when the cause is something negative, annoying, or problematic.

So in this sentence:

• gara-gara jalanan macet = because the roads were jammed / due to traffic

It often carries a slight feeling of blame or complaint.

For example:

• Saya kena marah gara-gara kamu. = I got scolded because of you.
• Acara batal gara-gara hujan. = The event was canceled because of the rain.

Both can mean because, but they are used a little differently.

• karena = neutral because
• gara-gara = because of, often with a negative/problematic cause

Compare:

• Saya telat ke kantor karena jalanan macet. = neutral
• Saya telat ke kantor gara-gara jalanan macet. = more conversational, slightly complaint-like

So gara-gara feels more like: I was late because of that traffic jam.

Jalan can mean:

• road/street
• to walk
• in some contexts, to run/function

In this sentence, jalanan refers to the roads / the streets / road conditions.

The suffix -an can sometimes make a word feel more like a thing, area, or collective everyday noun. Here, jalanan sounds natural when talking about the roads as a traffic environment.

So:

• jalan macet = possible, but less natural in this specific sentence
• jalanan macet = very natural for the roads were congested

Macet means jammed, congested, or stuck.

With traffic, it means there is a traffic jam or that traffic is not moving smoothly.

So:

• jalanan macet = the roads were jammed / there was heavy traffic

You can also hear:

• Lalu lintas macet. = Traffic is jammed.
• Jakarta macet banget. = Jakarta is really congested.

No. The sentence splits like this:

• Saya telat ke kantor = I was late to the office
• gara-gara jalanan macet = because the roads were jammed

So macet describes jalanan, not saya.

A very natural way to understand the sentence structure is:

[I was late to the office] [because the roads were jammed].

It is fairly informal to neutral spoken Indonesian.

Why?

• saya is polite/neutral
• telat is casual
• gara-gara is conversational

So the sentence sounds natural in everyday speech, but not especially formal.

A more formal version would be:

• Saya terlambat ke kantor karena jalanan macet.

That version is better for writing, formal speaking, or careful standard Indonesian.

Yes, if the context already makes it clear what you were late for.

• Saya telat karena jalanan macet. = I was late because the roads were jammed.

This is natural if the listener already knows you mean late to work, late to class, late to a meeting, etc.

But if you want to be specific, keep ke kantor.

Yes, that is possible.

For example:

• Gara-gara jalanan macet, saya telat ke kantor.

This means the same thing: Because the roads were jammed, I was late to the office.

This word order is also very natural. The choice is mostly about emphasis:

• Saya telat ke kantor gara-gara jalanan macet. → starts with the result
• Gara-gara jalanan macet, saya telat ke kantor. → starts with the cause

Yes, absolutely. It sounds natural.

A native speaker might also say variants such as:

• Saya telat ke kantor gara-gara macet.
• Saya terlambat ke kantor karena macet.
• Gara-gara macet, saya telat ke kantor.

All of these are common. The original sentence is very understandable and natural in everyday Indonesian.