Sebelum tamu datang, kami mengumpulkan sampah di halaman belakang.

Sebelum means before. It introduces a time clause:

• Sebelum tamu datang = before the guest(s) arrive / arrived

Indonesian often puts time information at the beginning of the sentence, just like English can:

• Before the guests arrive, we collect the trash in the backyard.

You can also reverse the order:

• Kami mengumpulkan sampah di halaman belakang sebelum tamu datang.

That means the same thing, though the original version puts more focus on the timing.

Indonesian does not use articles like a, an, or the the way English does.

So:

• tamu can mean a guest, the guest, or guests
• sampah can mean trash, the trash, or some trash

The exact meaning depends on context. This is very normal in Indonesian.

By itself, tamu can be singular or plural. Indonesian often leaves that unspecified unless it matters.

So sebelum tamu datang could mean:

• before the guest comes
• before the guests come

If you really want to make it clearly plural, you could say:

• para tamu = the guests
• tamu-tamu = guests

But in many everyday sentences, just tamu is enough.

This is a very important Indonesian distinction.

• kami = we, but not including the listener
• kita = we, including the listener

So in this sentence, kami mengumpulkan sampah means:

• we collected/collect the trash, but you are not part of the group

If the speaker wanted to include the person they are talking to, they would say kita instead.

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

So datang simply means come/arrive. The time is understood from context.

In this sentence, sebelum already gives the time relationship:

• before the guest(s) arrive
• before the guest(s) arrived

Both are possible depending on the larger context.

If needed, Indonesian can add time words such as:

• kemarin = yesterday
• besok = tomorrow
• sudah = already
• akan = will

But none are required here.

The base idea is kumpul, related to gathering.

But the form mengumpulkan is a transitive verb, meaning it takes an object:

• mengumpulkan sampah = to gather/collect trash

This is different from:

• berkumpul = to gather, to assemble (people gather themselves)
• kumpul = informal/root-like form, often used in speech

So:

• Kami mengumpulkan sampah = We collected trash.
• Kami berkumpul = We gathered.

The first is about collecting something. The second is about people assembling.

In many verbs, -kan helps form a transitive verb, often with the sense of causing, putting, or doing something to an object.

Here:

• kumpul = gather, be gathered
• mengumpulkan = gather/collect something

So mengumpulkan sampah means collect trash.

You do not need to translate -kan with a separate English word every time. It is better to learn mengumpulkan as a complete verb meaning to collect.

Because sampah usually works like a mass noun, similar to trash or garbage in English.

So:

• sampah = trash/garbage

It usually does not need a plural marker. Even if there are many pieces of trash, sampah is still natural.

If you reduplicated it as sampah-sampah, that would usually sound more marked or specific, like talking about different pieces/types of trash, not the normal default.

Literally:

• di = in / at
• halaman = yard / courtyard
• belakang = back / rear

So:

• di halaman belakang = in the backyard or in the back yard

A useful note: this di is a preposition, written separately.

Compare:

• di halaman belakang = in the backyard
• dikumpulkan = is collected / collected, where di- is a passive prefix and is written together

This is a common thing learners need to notice.

Yes. Halaman can mean different things depending on context:

• yard / courtyard
• page

With belakang, context tells you which one is meant.

In this sentence, because we are talking about collecting trash, halaman belakang clearly means:

• backyard
• rear yard

Not back page.

The comma is standard and helpful because Sebelum tamu datang is an introductory clause.

So this is good style:

• Sebelum tamu datang, kami mengumpulkan sampah di halaman belakang.

In very informal writing, people may leave the comma out, but using it is clearer and more natural in careful writing.

Yes. Para tamu clearly means the guests and makes the noun explicitly plural.

Compare:

• sebelum tamu datang = before the guest/guests arrive
• sebelum para tamu datang = before the guests arrive

Both are correct. The version without para is more neutral and often perfectly natural.

It is neutral and completely natural Indonesian.

It works well in writing and normal speech.

In casual spoken Indonesian, someone might say a more colloquial version such as:

• Sebelum tamu datang, kami ngumpulin sampah di halaman belakang.

Here ngumpulin is a spoken/informal version of mengumpulkan.

So the original sentence is a good standard form for learners to study.