Sebelum tamu datang, saya membersihkan remah biskuit di sofa.

Sebelum means before.

In this sentence, Sebelum tamu datang means Before the guest(s) came / Before the guests arrived.

It comes first because Indonesian often puts a time clause at the beginning to set the scene. This is very similar to English:

• Before the guests arrived, I cleaned...

You could also put it later:

• Saya membersihkan remah biskuit di sofa sebelum tamu datang.

That would still be correct.

Indonesian does not normally use articles like the or a/an.

So:

• tamu can mean guest or guests
• sofa can mean sofa or the sofa

The exact meaning depends on context. If the situation is already known, English may need the, but Indonesian usually does not.

It can mean either guest or guests.

Indonesian nouns do not have to change form for singular vs. plural. Context tells you which one is meant.

So:

• tamu datang = the guest came / the guests came

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

• para tamu = the guests
• tamu-tamu = guests (reduplication can mark plurality, though para tamu is often more natural for people)

Datang literally means come, but in many contexts it is naturally translated as arrive.

So:

• tamu datang = the guest came or the guest arrived

In this sentence, arrive is often the most natural English translation.

Membersihkan is a verb meaning to clean or to clean up something.

It comes from:

• bersih = clean (adjective)
• membersihkan = to clean / to make clean (verb)

So:

• Saya bersih = I am clean
• Saya membersihkan... = I cleaned / I was cleaning / I clean...

As for bersihkan:

• bersihkan! is often an imperative: clean it!
• saya bersihkan can mean I’ll clean it or let me clean it, depending on context

In this sentence, membersihkan is the normal form for describing the action.

The verb membersihkan has the affixes meN- and -kan attached to bersih.

Very roughly:

• bersih = clean
• membersihkan = to clean something / to make something clean

This pattern often creates an active transitive verb, meaning a verb that takes an object.

Here, the object is:

• remah biskuit = biscuit crumbs

So membersihkan remah biskuit means to clean up biscuit crumbs.

Remah biskuit means biscuit crumbs or cookie crumbs, depending on the variety of English you use.

Breakdown:

• remah = crumb / crumbs / small bits
• biskuit = biscuit

In Indonesian, noun combinations like this are common:

• remah roti = bread crumbs
• jus jeruk = orange juice
• kamar tidur = bedroom

So remah biskuit literally means crumbs of biscuit.

Di is a general location preposition, often translated as in, on, or at, depending on context.

So di sofa here most naturally means:

• on the sofa

Indonesian does not always distinguish as strictly as English does between in/on/at. Context makes the meaning clear.

So:

• remah biskuit di sofa = biscuit crumbs on the sofa

This is a very good question.

In the sentence saya membersihkan remah biskuit di sofa, di sofa tells you where the crumbs were.

So the meaning is:

• I cleaned up the biscuit crumbs on the sofa

If you want to emphasize that you removed the crumbs from the sofa, Indonesian can also say:

• Saya membersihkan remah biskuit dari sofa.

That makes the from idea more explicit.

So:

• di sofa = the crumbs are located on the sofa
• dari sofa = the crumbs were removed from the sofa

Both can work, but the original sentence is still natural.

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

So membersihkan by itself does not specifically mean cleaned, clean, or was cleaning. The time is understood from context.

In this sentence, the past meaning comes from the whole situation:

• Sebelum tamu datang suggests a sequence of events
• in English, this is naturally rendered as Before the guests arrived, I cleaned...

If needed, Indonesian can add time words such as:

• tadi = earlier
• kemarin = yesterday
• sudah = already

But they are not required here.

Yes. Indonesian word order is fairly flexible, especially with time expressions.

These are both natural:

• Sebelum tamu datang, saya membersihkan remah biskuit di sofa.
• Saya membersihkan remah biskuit di sofa sebelum tamu datang.

The first version emphasizes the time frame first. The second starts with the main action.

The comma is not always strictly necessary in informal writing, but it is very helpful and standard here because the sentence begins with a subordinate time clause:

• Sebelum tamu datang, ...

This is similar to English, where a comma is commonly used after an introductory clause:

• Before the guests arrived, I cleaned...

So the comma is a good choice.

Yes. Sebelum para tamu datang is correct and makes it clearly plural:

• para tamu = the guests

So:

• Sebelum tamu datang = before the guest(s) came
• Sebelum para tamu datang = before the guests came

Using para is especially common for groups of people.

Not exactly in every variety of English.

In Indonesian, biskuit usually refers to a dry baked snack, and in many contexts it may match:

• biscuit in British English
• cookie or sometimes cracker in American English, depending on the item

So remah biskuit could be translated as:

• biscuit crumbs
• cookie crumbs

The best translation depends on what kind of snack you imagine.

Yes, but the meaning changes.

• membersihkan sofa = clean the sofa
• membersihkan remah biskuit di sofa = clean up the biscuit crumbs on the sofa

The original sentence focuses on what was being cleaned up: the crumbs.
If you say membersihkan sofa, the sofa itself becomes the direct object.

Indonesian often leaves things less specific unless the speaker wants to be specific.

So tamu datang is enough to mean:

• the guest came
• the guests came
• guests arrived

If you want to be more specific, you can add:

• tamu itu = that guest / the guest
• mereka = they
• para tamu = the guests

But the shorter version is very natural.

In standard Indonesian, including saya is normal and clear.

Sometimes the subject can be omitted if it is obvious from context, especially in conversation:

• Sebelum tamu datang, membersihkan remah biskuit di sofa.

But that sounds incomplete or less standard by itself.
For a full sentence, saya is the best choice here:

• Sebelum tamu datang, saya membersihkan remah biskuit di sofa.