Semak berat badannya.

It is an imperative sentence, so it gives a command or instruction.

The understood subject is you, but Malay usually leaves it out in commands. So the structure is basically:

Semak = check
berat badannya = his/her body weight

So the full sense is Check his/her weight.

Semak means check, review, or verify.

In this sentence, it suggests checking someone's weight, possibly by:

• looking at a record,
• confirming a measurement,
• or making sure the information is correct.

If you mean actually weigh the person on a scale, Malay often uses timbang instead:

• Timbang berat badannya. = Weigh his/her body weight / weigh the person

So semak is more like check, while timbang is more specifically weigh.

In Malay, many words can function in more than one way depending on context.

berat can mean:

• heavy as an adjective
• weight as a noun-like idea

Examples:

• Beg itu berat. = That bag is heavy.
• Berat badannya... = His/her body weight...

So in Semak berat badannya, berat is being used in the sense of weight, not heavy.

Yes, berat badan is a very common expression meaning body weight.

Literally:

• berat = weight
• badan = body

So:

• berat badan = body weight

That is why berat badannya is natural: it means his/her body weight.

badannya = badan + -nya

• badan = body
• -nya = his/her/its, and sometimes also gives a definite sense

So badannya literally means his/her body.

In the full phrase:

• berat badannya = the weight of his/her body, which is naturally translated as his/her weight

Because those mean different things.

• berat badannya = his/her body weight
• badannya berat = his/her body is heavy

So:

1. berat badannya is a noun phrase

   • it names a thing: his/her weight

2. badannya berat is a full statement

   • it describes the body: his/her body is heavy

This word order difference is very important in Malay.

It can mean his, her, or its. Malay does not usually mark gender the way English does.

So badannya could mean:

• his body
• her body
• sometimes its body, depending on context

In your sentence, the correct English choice depends on who is being talked about.

Yes, you could, if the context is already clear.

• Semak beratnya. = Check his/her/its weight.
• Semak berat badannya. = Check his/her body weight.

The version with badannya is more specific and clearer when talking about a person.
beratnya by itself can be more ambiguous, because it could refer to the weight of almost anything.

By itself, it is fairly direct, because it is a plain command.

That is normal in:

• instructions
• medical notes
• checklists
• workplace directions

If you want to make it more polite, you can add:

• Sila = please
• Tolong = please / help

For example:

• Sila semak berat badannya.
• Tolong semak berat badannya.

These sound softer and more polite than the bare Semak berat badannya.

Yes. In casual speech, speakers might use other patterns, such as:

• Semak berat badan dia.
• Periksa berat badan dia.
• Timbang dia. if the meaning is specifically weigh the person

A few notes:

• dia is common in everyday speech for he/she
• -nya often sounds a bit more compact or slightly more formal/written
• periksa is another common verb meaning inspect/check

So your sentence is correct, but depending on context, a native speaker might choose a different verb or pronoun form.