Learn Hardcore Malay: Sepupu saya berpesan supaya saya sentiasa menjaga kesihatan. - My cousin advised me to always take care of my health.

berpesan is a verb with the ber- prefix that conveys “to advise,” “to caution,” or “to urge someone to do something out of care or concern.” In contrast, pesan alone can be:

a noun meaning message or order,
or a verb meaning to order/command or to send a message.
Using berpesan focuses specifically on the act of giving advice or a warning.

What role does supaya play in the sentence? Can I replace it with agar or untuk?

supaya is a conjunction meaning “so that” or “in order that,” used to link the main clause with its purpose or result.

You can replace supaya with agar without changing the meaning (though agar is slightly more formal):
Sepupu saya berpesan agar saya sentiasa menjaga kesihatan.
You generally do not use untuk here, because untuk + verb forms an infinitive phrase rather than introducing a full purpose clause after verbs of advising.

Why is saya repeated after supaya? Is it necessary?

Repeating saya clarifies that the advice is directed at you (the speaker). While Malay often omits repeated subjects when context is clear, including saya:

avoids ambiguity about whose health to care for,
emphasizes that you are the one who must always maintain your health.

What kind of clause does supaya introduce?

It introduces a purpose clause (sometimes called a result clause). The structure is:
Main clause (advice) + supaya + Dependent clause (intended outcome).
Here, “supaya saya sentiasa menjaga kesihatan” spells out the intended outcome of the advice.

Where should sentiasa be placed? Can its position change?

sentiasa is an adverb of frequency (“always,” “constantly”) and typically appears before the verb:

Standard: saya sentiasa menjaga kesihatan
Less common (but understandable): sentiasa saya menjaga kesihatan
Avoid splitting the verb–object pair: saya menjaga sentiasa kesihatan is incorrect.

Why is menjaga used instead of jaga? Can I omit the meN- prefix?

menjaga is the standard active verb “to take care of.”
In informal speech, Malay speakers often drop the prefix and say jaga kesihatan.
In formal writing or polite contexts, stick with menjaga.

What is the literal meaning of menjaga kesihatan, and how do I translate it into English?

Literally, menjaga kesihatan means “to guard health.” In English we normally say:

“to take care of one’s health”
“to maintain good health.”

How could I express the same idea in a more casual or direct-speech style?

You can simplify and use direct speech or colloquial forms:

Direct speech: Sepupu saya pesan, "Jaga kesihatan selalu, ya!"
Colloquial: Sepupu saya pesan jaga kesihatan.

Is the sentence formal or informal? Where can I use it?

The original sentence is neutral to moderately formal. It’s suitable for:

Written texts (emails, reports)
Polite conversation or speeches
For very casual settings, you can simplify by dropping ber-, supaya, or repeating pronouns.