Polis menyiasat kemalangan itu.

The word order is Subject + Verb + Object, which is very similar to English:

• Polis = the police
• menyiasat = investigate / are investigating
• kemalangan itu = that accident / the accident

So the structure is:

Polis + menyiasat + kemalangan itu
The police + investigate/are investigating + the accident

Polis usually means the police in a general sense, or police officers collectively. In this sentence, it most naturally means the police.

Malay nouns do not always show singular/plural clearly from the form alone, so polis can refer to police generally without changing shape.

If you specifically wanted to say a police officer, Malay often uses seorang polis or more commonly pegawai polis depending on context.

Malay does not use articles like a, an, and the in the same way English does.

So:

• polis can mean police / the police
• kemalangan can mean an accident / accident / the accident, depending on context

In this sentence, itu helps make kemalangan definite, so kemalangan itu means that accident or the accident.

Itu means that, and in Malay it usually comes after the noun it describes.

So:

• kemalangan itu = that accident
• literally: accident that

This is normal in Malay. Demonstratives like ini (this) and itu (that) usually follow the noun:

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

In many contexts, itu can also make something sound definite, so kemalangan itu may be understood as the accident as well.

Menyiasat means to investigate.

In this sentence, it is the active verb:
Polis menyiasat kemalangan itu = The police are investigating that accident / The police investigate that accident

It comes from the root siasat, which is related to investigation or investigate.

Malay often adds prefixes to roots to form verbs. Here, the root is siasat, and the prefix meN- creates an active verb.

So:

• siasat = investigate / investigation-related root
• menyiasat = to investigate

This change is part of a very common Malay pattern. With roots beginning with s, the meN- prefix often becomes meny-, and the original s drops:

• siasat → menyiasat

This is a normal sound and spelling change in Malay word formation.

Malay verbs do not change form for tense the way English verbs do.

So menyiasat by itself does not specifically mark past, present, or future. The time is understood from context or from time words.

Depending on context, Polis menyiasat kemalangan itu could mean:

• The police investigate that accident
• The police are investigating that accident
• sometimes even The police investigated that accident, if the context makes the time clear

If Malay needs to be more specific, it can add time words such as:

• sedang = in progress / currently
• telah or sudah = already / completed
• akan = will

For example:

• Polis sedang menyiasat kemalangan itu = The police are investigating the accident.
• Polis telah menyiasat kemalangan itu = The police investigated / have investigated the accident.

Yes. In many contexts, kemalangan itu can be translated as either that accident or the accident.

Why? Because itu literally means that, but in actual usage it can also make a noun definite when both speaker and listener know which thing is being referred to.

So the best English translation depends on context:

• if pointing out a specific accident: that accident
• if referring to an already known accident: the accident

A simple approximate pronunciation is:

men-yee-ah-saht

A rough breakdown:

• me = like muh or meh
• nyi = like nyi in canyon for the ny sound, followed by ee
• a = ah
• sat = saht

Also:

• ny in Malay is a single consonant sound, like ñ in Spanish señor
• vowels are usually pronounced clearly and separately

So menyiasat is spoken in smooth syllables, roughly: me-nya-sat.

Kemalangan most commonly means accident, especially something like a traffic accident or mishap.

In this sentence, that is definitely the meaning: Polis menyiasat kemalangan itu = The police are investigating the accident

Depending on context, it can sometimes refer more generally to a misfortune or an unfortunate incident, but accident is the most straightforward meaning here.

In standard Malay, menyiasat is the normal full verb form here, so Polis menyiasat kemalangan itu is the best standard sentence.

You may sometimes see or hear shorter, more headline-like or informal styles such as polis siasat..., especially in news headlines, where Malay often drops prefixes to sound brief and punchy.

So:

• Polis menyiasat kemalangan itu = standard full sentence
• Polis siasat kemalangan itu = possible in headlines or compressed style, but less formal as a normal sentence

Malay does not have to mark plural nouns the way English often does.

A noun can stay the same whether it is singular or plural, and the meaning is understood from context.

So:

• polis can refer to police generally
• kemalangan can mean accident or accidents, depending on context

If Malay wants to make plurality very clear, it can use reduplication or other words, but it is not necessary here.

In this sentence, kemalangan itu is most naturally understood as that accident / the accident, singular.

Yes. If the context is a road accident or collision, kemalangan can often be translated naturally as accident or crash.

So possible English translations include:

• The police are investigating the accident
• The police are investigating that accident
• The police are investigating that crash

The best choice depends on the situation and on how specific or natural you want the English to sound.