Datuk dia tua.

Malay often leaves out the verb to be when the predicate is an adjective or a noun.

So Datuk dia tua literally looks like Grandfather his/her old, but the natural English meaning is His/Her grandfather is old.

This is completely normal in Malay:

• Dia marah = He/She is angry
• Rumah itu besar = That house is big

Here, dia means his or her.

Even though dia is often taught first as he/she, it can also show possession when it comes after a noun:

• rumah dia = his/her house
• kawan dia = his/her friend
• datuk dia = his/her grandfather

So in this sentence, datuk dia means his grandfather or her grandfather.

Malay dia is gender-neutral. It can mean he, she, him, her, his, or her, depending on context.

So Datuk dia tua can mean either:

• His grandfather is old
• Her grandfather is old

Malay usually does not mark gender unless the speaker adds extra information.

In Malay, possessors often come after the noun.

So Malay says:

• rumah dia = his/her house
• ibu saya = my mother
• nama mereka = their name

That is different from English, where the possessor usually comes first:

• his house
• my mother
• their name

So datuk dia follows normal Malay word order for possession.

In this sentence, datuk means grandfather.

A useful warning: Datuk can also be an honorific title in Malaysia, similar to a title of distinction. But in Datuk dia tua, if the meaning has already been given as a family sentence, then it is clearly grandfather.

Also, because Datuk is the first word of the sentence, it is capitalized anyway. That capitalization does not automatically mean it is the title.

Here tua is the predicate adjective, meaning it is the part that tells you something about datuk dia.

The structure is:

• Datuk dia = the subject, his/her grandfather
• tua = the predicate, old

So the sentence means:

• His/Her grandfather is old

This is slightly different from a noun phrase like the old grandfather. In Malay, a clearer way to say that as a noun phrase would often be datuk yang tua.

Yes, it is understandable and natural, especially in speech.

However, native speakers might also say:

• Datuknya tua
• Datuknya sudah tua

These can sound a bit smoother or more compact, especially in writing.

A rough comparison:

• datuk dia = his/her grandfather
• datuknya = also his/her grandfather, with -nya attached to the noun

And:

• sudah tua adds the sense of already old or simply makes the statement sound a bit more complete in many contexts.

Yes. Datuknya tua is a very common alternative.

The ending -nya can stand for his/her in this kind of sentence:

• ibunya = his/her mother
• rumahnya = his/her house
• datuknya = his/her grandfather

So:

• Datuk dia tua
• Datuknya tua

both can mean His/Her grandfather is old.

The version with -nya is often more concise and may sound more natural in standard written Malay.