Nombor PIN ini rahsia.

Malay often leaves out the verb to be in simple present-tense sentences.

So where English says This PIN number is secret, Malay can simply say:

• Nombor PIN ini rahsia.

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

In more formal styles, you may sometimes see adalah or ialah, but in a short everyday sentence like this, leaving the copula out is the most natural choice.

In Malay, demonstratives such as ini and itu usually come after the noun phrase, not before it.

So:

• nombor PIN ini = this PIN number
• nombor PIN itu = that PIN number

This is a very common pattern in Malay:

• buku ini = this book
• rumah itu = that house

So the order is not like English this PIN number, but rather PIN number this.

Yes. Nombor PIN ini is one noun phrase.

Its structure is:

• nombor PIN = PIN number
• ini = this

Together:

• nombor PIN ini = this PIN number

Then rahsia is the predicate describing it.

So the sentence breaks down like this:

• [Nombor PIN ini] [rahsia]
• subject
  • description

Here, rahsia functions like an adjective-like predicate meaning secret.

Malay is flexible about words like this. A word can often behave like an adjective or noun depending on context.

In this sentence, rahsia is describing nombor PIN ini, so it works much like an adjective in English:

• Nombor PIN ini rahsia.
• This PIN number is secret.

You do not need anything extra before rahsia.

Yes, you could, but it sounds more formal or emphatic.

• Nombor PIN ini rahsia. = simple, natural, everyday
• Nombor PIN ini adalah rahsia. = more formal or written

In normal conversation, the shorter version is usually better.

Also note that learners are often told about adalah and ialah, but in many basic descriptive sentences, native usage simply omits them.

This is similar to English phrases like PIN number, ATM machine, or PDF file. Even though the abbreviation already includes that word, people still commonly say the full everyday phrase.

So nombor PIN is a natural phrase in Malay, just as PIN number is common in English.

In real usage, people may also simply say:

• PIN ini rahsia.

That is also natural.

Yes. Nombor is a borrowing related to English number, adapted to Malay spelling and pronunciation.

A useful note:

• Standard Malay in Malaysia usually uses nombor
• Indonesian usually uses nomor

So nombor PIN ini rahsia looks specifically Malaysian/Malay-standard.

Yes, depending on context.

Malay does not always mark the difference between:

• secret as an adjective
• a secret as a noun

In this sentence, rahsia is best understood as secret.

If the sentence were in a different structure, rahsia could also act more like a noun. Context usually makes the meaning clear.

No, not really.

• Nombor PIN ini rahsia = This PIN number is secret
• Ini nombor PIN rahsia would be understood more like This is a secret PIN number or could sound incomplete/odd depending on context.

The original sentence is specifically saying something about nombor PIN ini.
So the original word order matters.

You would usually use tidak before rahsia:

• Nombor PIN ini tidak rahsia.

That means This PIN number is not secret.

This works because rahsia is functioning as a descriptive predicate here, and tidak is used to negate adjectives and verbs.

A common formal way is:

• Adakah nombor PIN ini rahsia?

That means Is this PIN number secret?

In conversation, intonation can also do the job:

• Nombor PIN ini rahsia?

That is less formal and depends on speech context, but it is very common in everyday Malay.

Yes. It is short, grammatical, and natural.

Depending on context, a speaker might also say:

• PIN ini rahsia.
• Nombor PIN ini adalah rahsia.
• PIN ini sulit.

But Nombor PIN ini rahsia is perfectly good Malay and follows a very common sentence pattern:

• noun phrase + predicate

So it is a useful model sentence for learners.