Pas tamu datang, saya menuang kopi dari teko kecil ke termos supaya tetap hangat.

Here pas means when or just as.

So Pas tamu datang means something like:

• When the guest(s) arrived
• Just as the guest(s) came

A useful thing to know is that pas is fairly informal in this meaning. In more formal or neutral Indonesian, you might also see:

• saat tamu datang
• ketika tamu datang

Also, pas has other meanings in other contexts, such as exactly right or fitting, so context matters.

Indonesian often leaves nouns bare, without words like a, the, or explicit plural marking, unless the speaker wants to be more specific.

So tamu datang can mean:

• a guest came
• the guest came
• guests came
• the guests came

The exact meaning depends on context.

If you wanted to be more specific, you could say:

• seorang tamu datang = a guest came
• para tamu datang = the guests / guests came (clearly plural)

But in natural Indonesian, the simple tamu datang is very normal.

It can be translated as either come or arrive, depending on context.

• datang basically means to come / to arrive
• In this sentence, English might naturally use arrived
• But the core Indonesian idea is just that the guest(s) came

Compare:

• Tamu datang. = The guest came / The guest arrived.
• Dia datang ke rumah saya. = He/She came to my house.

So datang covers both ideas more broadly than English sometimes does.

Menuang is the active verb form built from the root tuang.

• tuang = the base idea of pour
• menuang = to pour in an active verb sentence

The prefix here is meN-, which changes form depending on the first sound of the root. With tuang, it becomes men-, and the t drops:

• meN- + tuang → menuang

This is a very common Indonesian pattern.

In this sentence:

• saya menuang kopi = I pour / poured coffee

If you just said tuang!, that would sound more like a command:

• Tuang kopinya! = Pour the coffee!

By itself, menuang does not mark tense the way English does.

So saya menuang kopi could mean different things depending on context:

• I poured coffee
• I pour coffee
• I was pouring coffee

In this sentence, many English translations would probably choose a past form like I poured or I was pouring, because the event sounds like part of a past situation.

This is very common in Indonesian: time is usually understood from context, not from verb endings.

Because in Indonesian, adjectives usually come after the noun.

So:

• teko kecil = small teapot
• rumah besar = big house
• kopi panas = hot coffee

This is different from English, where adjectives usually come before the noun.

So the order is:

• teko = teapot
• kecil = small

Literally: teapot small

They show movement:

• dari = from
• ke = to

So:

• dari teko kecil = from the small teapot
• ke termos = to the thermos

This creates a very clear path:

from the teapot to the thermos

That is exactly how Indonesian often expresses transfer or motion.

Yes, you could.

• ke termos = to the thermos
• ke dalam termos = into the thermos

The version with ke dalam is a bit more explicit about the coffee going inside the thermos.

In everyday Indonesian, ke termos is often enough, because the meaning is already obvious. But ke dalam termos is also perfectly natural.

Termos means a thermos or vacuum flask.

It refers to an insulated container used to keep drinks hot or cold.

So in this sentence, the speaker is pouring coffee into a thermos so it stays warm.

You may also hear related expressions like:

• botol termos = thermos bottle
• air panas dalam termos = hot water in a thermos

Supaya means so that or in order that.

It introduces a purpose:

• saya menuang kopi ... ke termos supaya tetap hangat
• I pour/poured the coffee ... into the thermos so that it stays/stayed warm

So the second part explains why the speaker poured the coffee into the thermos.

A very similar word is agar:

• supaya tetap hangat
• agar tetap hangat

Both mean so that it remains warm.

Tetap means remain, stay, or keep being.

• hangat = warm
• tetap hangat = stay warm / remain warm

So this phrase does not mean become warm. It means the coffee is already warm, and the speaker wants it to continue being warm.

That distinction is important:

• menjadi hangat = become warm
• tetap hangat = stay warm

Yes, the understood subject is the coffee.

In Indonesian, it is very common to leave out words that are obvious from context. So after mentioning kopi, the sentence does not need to repeat it.

The full logic is:

• Saya menuang kopi dari teko kecil ke termos supaya kopi tetap hangat.

But repeating kopi is unnecessary, so natural Indonesian often leaves it out:

• ... supaya tetap hangat.

This kind of omission is very common and very normal.

Both can mean I, but they differ in tone and formality.

• saya = more neutral, polite, standard
• aku = more casual, personal, intimate

So saya is a safe, standard choice and works well in most situations, including written Indonesian.

If the sentence were in a very casual context, you might hear:

• Pas tamu datang, aku menuang kopi ...

That is also possible, but it sounds less formal.

It is mostly neutral, but pas makes it a bit more conversational.

Parts like these are neutral:

• saya
• menuang
• supaya

But pas is more spoken and informal than saat or ketika.

So the sentence sounds natural and everyday, not slangy, but not especially formal either.

A more formal-sounding version would be:

• Saat tamu datang, saya menuang kopi dari teko kecil ke termos agar tetap hangat.

The comma separates the opening time clause from the main clause.

• Pas tamu datang = time clause
• saya menuang kopi ... = main clause

So the comma helps the reader see the structure clearly:

When the guest(s) arrived, I poured coffee...

In Indonesian, this comma is natural and helpful, especially when the subordinate clause comes first.

Yes. In this sentence, supaya and agar are both natural.

• supaya tetap hangat
• agar tetap hangat

Both mean so that it stays warm.

A rough tendency is:

• agar can sound a bit more formal or written
• supaya can sound a bit more everyday

But in many contexts, they are interchangeable.

Yes, but the meaning changes a little.

• hangat = warm
• panas = hot

So:

• supaya tetap hangat = so it stays warm
• supaya tetap panas = so it stays hot

For coffee in a thermos, either could make sense, depending on what you want to emphasize. Hangat often feels a little softer and more moderate than panas.

Yes, it is very natural.

The structure is straightforward:

• menuang kopi = pour coffee
• dari teko kecil = from the small teapot
• ke termos = into/to the thermos

Indonesian often expresses this kind of action very directly with:

verb + object + dari ... ke ...

So this sentence is a good example of ordinary, natural Indonesian word order.