Sumpah itu sangat penting.

In Malay, demonstratives like ini (this) and itu (that/the) usually come after the noun.

• sumpah itu = that oath / the oath
• buku ini = this book

This is the normal word order in Malay, even though English puts this/that before the noun.

Malay often leaves out the verb to be when linking a subject to an adjective or noun.

So:

• Sumpah itu sangat penting.
  literally: That oath very important.

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

Sangat means very and intensifies the adjective that follows it.

• penting = important
• sangat penting = very important

In Malay, sangat usually comes before the adjective:

• sangat besar = very big
• sangat susah = very difficult

Yes. Penting is an adjective meaning important.

In this sentence, it works as the predicate adjective:

• Sumpah itu = the subject
• sangat penting = what is being said about it

So the structure is basically:

• [noun phrase] + [adverb + adjective]

Not always. Sumpah can have a few related meanings depending on context, such as:

• oath
• vow
• curse
• in casual speech, something like I swear

In Sumpah itu sangat penting, the most natural sense is oath or vow, because it is being treated as an important thing.

Yes. In many contexts, itu can feel like either that or the in English.

So sumpah itu may be understood as:

• that oath
• the oath

Which one sounds better in English depends on the context. Malay does not use articles in the same way English does, so itu can help make something definite or specific.

You can, but it changes the feel.

• Sumpah itu sangat penting. = a specific oath is very important
• Sumpah sangat penting. = oaths/swearing/oath-taking is very important, or a more general statement

Without itu, the noun becomes less specifically tied to one particular oath. Whether it sounds natural depends on context.

That is the normal Malay pattern for this kind of sentence. A common structure is:

• subject + adjective
• subject + adverb + adjective

So:

• Rumah itu besar. = The house is big.
• Buku ini mahal. = This book is expensive.
• Sumpah itu sangat penting. = That oath is very important.

This is different from English, where you need is before the adjective.

A simple learner-friendly pronunciation guide is:

• sumpah ≈ soom-pah
• itu ≈ ee-too
• sangat ≈ sah-ngat
• penting ≈ pen-ting

A few notes:

• u is usually like oo in food
• a is usually like the a in father
• ng in sangat and penting is like the ng in sing

Malay pronunciation is generally quite regular compared with English.

No, you do not need either one here.

Sumpah itu sangat penting is already a complete and natural sentence.

In ordinary Malay, sentences with adjectives usually do not use a copula. In formal writing, you may sometimes see adalah, but in a sentence like this it is usually unnecessary. For a learner, the safest and most natural version is simply:

• Sumpah itu sangat penting.

You can negate the adjective with tidak:

• Sumpah itu tidak penting. = That oath is not important.
• Sumpah itu tidak begitu penting. = That oath is not so important.
• Sumpah itu tidak sangat penting. is less natural than the versions above.

A very common pattern is:

• tidak + adjective

The grammar is neutral and standard.

The word sumpah can sound formal if it really means an oath or vow, especially in legal, religious, or serious contexts. But sumpah also appears in casual spoken Malay with different shades of meaning.

So the sentence itself is grammatically standard, but its tone depends on what kind of sumpah is being talked about.

The normal order is:

• Sumpah itu sangat penting.

You might see or hear changed word order for emphasis in poetry, rhetoric, or marked speech, but for everyday standard Malay, keep the usual order.

So as a learner, it is best to use:

• subject + sangat + adjective

No, not automatically. Sumpah by itself does not show singular or plural the way English nouns often do.

In this sentence, sumpah itu is most naturally understood as one specific oath because of the context and the use of itu. But Malay generally relies heavily on context rather than changing the noun form.

If you really needed to mark plurality, Malay might use reduplication or other wording, depending on context.