Kalau saya tidak sarapan, saya keburu lapar di kantor.

Kalau means if. It introduces the condition:

Kalau saya tidak sarapan = If I don't eat breakfast

In everyday Indonesian, kalau is very common and natural. You might also see jika or bila, but those usually sound more formal.

Use tidak to negate verbs and adjectives.

Here, sarapan is functioning like a verb, so:

tidak sarapan = not have breakfast

Bukan is mainly used to negate nouns or noun phrases, for example:

Saya bukan dokter = I am not a doctor

So tidak is the correct choice in this sentence.

Here, sarapan is a verb, meaning to have breakfast.

So:

saya tidak sarapan = I don't have breakfast

This is very normal in Indonesian. Sarapan can also be a noun in other contexts, where it means breakfast itself.

Examples:

• Saya sarapan jam 7 = I have breakfast at 7
• Sarapan saya roti = My breakfast is bread

Indonesian often repeats the subject in both clauses for clarity:

Kalau saya tidak sarapan, saya keburu lapar di kantor.

This is similar to English: If I don't eat breakfast, I get hungry at the office.

Even though both clauses have the same subject, repeating saya sounds clear and natural. Indonesian does not always drop repeated subjects the way some languages do.

Yes, sometimes.

A very natural shorter version is:

Kalau tidak sarapan, saya keburu lapar di kantor.

Here the subject in the first clause is understood from the second clause. This works well in conversation.

But the full version with both saya is also completely natural, especially when you want to sound clear or slightly more explicit.

Keburu is the trickiest word in the sentence.

It often gives the idea of something happening too soon, earlier than wanted, or already by the time something else happens.

So saya keburu lapar di kantor suggests something like:

• I get hungry too soon at the office
• By the time I'm at the office, I'm already hungry
• I end up getting hungry at the office sooner than I want

There is a slight feeling that this is inconvenient or undesirable.

Most naturally, di kantor tells you the place where the problem shows up: at the office.

So the sentence means that if you skip breakfast, you will end up hungry when you are at the office.

Because of keburu, there is also a nuance of already being hungry by that point. So the idea is not just simple location, but also timing: by the time you're at the office, you're already hungry.

In Indonesian, adjectives can often function directly as predicates.

So:

saya lapar = I am hungry

You do not need a separate word for am.

In this sentence, lapar is the state being reached: saya keburu lapar = I end up hungry too soon / I get hungry too soon

English usually needs extra wording, but Indonesian often does not.

Di kantor means at the office or in the office.

Here di is a preposition meaning in/at/on, so it is written separately from the noun:

di kantor

This is different from the prefix di- used in passive verbs, which is written together:

• ditulis = written
• dibaca = read

A good rule:

• di + place → separate
• di- + verb → attached

Indonesian often leaves tense and time reference to context.

In this sentence, the conditional structure already makes the meaning clear: If I don't eat breakfast, I get/will get hungry at the office.

Because of that, akan is not necessary.

You could say:

Kalau saya tidak sarapan, saya akan keburu lapar di kantor.

But in many everyday situations, that sounds less natural than the version without akan.

Yes. You can also say:

Saya keburu lapar di kantor kalau saya tidak sarapan.

This still means the same thing.

However, putting the kalau clause first is very common when you want to present the condition before the result:

• If I don't eat breakfast, ...
• then the consequence follows

So the original order sounds very natural.