Sumpah itu sangat penting.

A natural breakdown is:

• sumpah = oath, vow
• itu = that, the
• sangat = very
• penting = important

So literally it is something like oath that very important, but in natural English it becomes That oath is very important or The oath is very important.

In Indonesian, a present-tense to be verb is often omitted, especially in simple statements where one thing is being described.

So:

• Sumpah itu sangat penting = That oath is very important
• literally, Indonesian just puts the subject and description together

This is very normal. You do not need a separate word for is here.

In Indonesian, demonstratives like ini and itu usually come after the noun.

So:

• sumpah itu = that oath
• rumah itu = that house
• buku itu = that book

This is one of the most noticeable differences from English word order.

It can function like either one, depending on context.

In many sentences, itu literally means that. But in natural translation, it can also make the noun definite, so English may use the.

So sumpah itu could be understood as:

• that oath
• the oath

The exact choice depends on the situation and on the translation style.

Sangat means very and intensifies the adjective that follows it.

Here it modifies penting:

• penting = important
• sangat penting = very important

This is a very common pattern in Indonesian:

• sangat bagus = very good
• sangat besar = very big
• sangat sulit = very difficult

In Indonesian, words like sangat usually come before the adjective they modify.

So:

• sangat penting = very important
• sangat cepat = very fast

This is similar to English, where very also comes before the adjective.

Yes. Both are possible.

• sangat penting = very important
• penting sekali = very important

Both are common, but they can feel slightly different in tone:

• sangat penting is very straightforward and neutral
• sekali often adds a bit more emphasis in spoken language

So Sumpah itu sangat penting and Sumpah itu penting sekali are both correct.

Here, sumpah is a noun, meaning oath or solemn vow.

It is the thing being talked about in the sentence.

That matters because sumpah can also appear in other uses, especially in casual speech, where it can relate to I swear or seriously. But in this sentence, because it is followed by itu and functions as the topic of the sentence, it is clearly a noun: the oath / that oath.

Not exactly.

• janji = promise
• sumpah = oath, sworn vow

A sumpah usually sounds stronger, more formal, or more solemn than janji. It can carry a sense of swearing something seriously, sometimes in legal, religious, or ceremonial contexts.

So sumpah itu sangat penting sounds weightier than janji itu sangat penting.

Because it describes sumpah.

In this sentence:

• sumpah itu = the oath / that oath
• sangat penting = very important

So penting is giving a quality or description of the noun. That makes it an adjective here.

Yes, it is natural and grammatical.

It sounds like a clear, standard sentence you might see in speech or writing. Depending on context, it could be used in discussions about:

• a formal oath
• a promise with serious consequences
• law, politics, religion, or ceremony

It is simple, direct, and normal Indonesian.

A simple pronunciation guide is:

• sumpah ≈ SOOM-pah
• itu ≈ EE-too
• sangat ≈ SAH-ngat
• penting ≈ pen-TING

A rough full pronunciation:

SOOM-pah EE-too SAH-ngat pen-TING

A few notes:

• u is usually like oo in food
• a is usually like a in father
• ng is like the sound in sing

In standard Indonesian, sumpah itu sangat penting is the normal order.

Putting itu before the noun is generally not the regular pattern for this kind of sentence. Native learners of Indonesian should get used to:

• noun + ini/itu

So:

• sumpah itu = correct, standard
• itu sumpah = not the normal way to say that oath in this context

It is neutral and standard.

None of the words are slang, and the grammar is normal formal Indonesian. It would work in:

• conversation
• writing
• speeches
• educational material

The word sumpah itself may sound serious because of its meaning, but the sentence structure is not especially formal or informal.