Setelah makan di mobil, ada remah roti di kursi, jadi saya membersihkannya dengan saputangan.

Yes, the subject is understood rather than stated.

Setelah makan di mobil literally means after eating in the car. Indonesian often leaves out the subject when it is obvious from context. In this sentence, we naturally understand it as:

After eating in the car, ...

The eater is assumed to be the same person later referred to as saya.

A fuller version could be:

Setelah saya makan di mobil, ...

But that is often unnecessary in natural Indonesian.

Di mobil means in the car.

Here it most naturally goes with makan, so:

Setelah makan di mobil = After eating in the car

So the idea is that the eating happened in the car. Because of that, there were bread crumbs on the seat afterward.

Ada means there is / there are / exist.

So:

ada remah roti di kursi = there are bread crumbs on the seat

This is a very common Indonesian pattern:

ada + noun + location

Examples:

• Ada buku di meja. = There is a book on the table.
• Ada orang di luar. = There is someone outside.

Both can be understood, but ada remah roti di kursi is the more natural way to introduce the existence of something.

It follows the common existential pattern:

ada + thing + place

So:

• Ada remah roti di kursi. = There are bread crumbs on the seat.

If you say remah roti ada di kursi, it sounds more like you are specifically talking about the crumbs and saying where they are, almost like the crumbs are on the seat.

Remah means crumb or small fragment, and roti means bread.

So remah roti means bread crumbs.

Indonesian often uses noun + noun combinations like this:

• air mata = tears
• rumah sakit = hospital
• remah roti = bread crumbs

Even though English uses plural crumbs, Indonesian does not need to mark plural here.

Not necessarily.

Indonesian often does not mark plurals if the meaning is already clear from context. So:

remah roti can already mean bread crumbs.

If you say remah-remah roti, that can emphasize multiple little crumbs, but it is not required.

So both are possible, but remah roti is perfectly normal.

Here jadi means so or therefore.

It connects the two ideas:

• there were bread crumbs on the seat
• so I cleaned them

So:

jadi saya membersihkannya = so I cleaned it/them

In conversation, jadi is very common as a connector.

Membersihkannya can be broken down like this:

• bersih = clean
• meN- ... -kan → membersihkan = to clean something
• -nya = it / them

So:

membersihkannya = to clean it / to clean them

In the sentence:

saya membersihkannya = I cleaned it / them

This is a good example of how Indonesian uses affixes to build verbs.

Here -nya refers to the thing being cleaned, most naturally the bread crumbs or possibly the mess from the bread crumbs.

So in natural English, it would usually be translated as:

I cleaned them or I cleaned it up

Even though -nya is singular-looking in many textbook explanations, in real Indonesian it can refer to:

• him/her
• it
• them
• sometimes even something already understood from context

It could be repeated, but using -nya is more natural and less repetitive once the object has already been mentioned.

Compare:

• Ada remah roti di kursi, jadi saya membersihkannya.
• Ada remah roti di kursi, jadi saya membersihkan remah roti itu.

The second is grammatical, but the first sounds smoother and more natural because Indonesian often uses -nya to refer back to something already mentioned.

Dengan means with / using.

Saputangan means handkerchief.

So:

dengan saputangan = with a handkerchief / using a handkerchief

Here dengan introduces the instrument used to do the cleaning.

Similar examples:

• Saya menulis dengan pena. = I write with a pen.
• Dia memotongnya dengan pisau. = He/She cut it with a knife.

Literally, di is a general location marker that can mean in, on, at, depending on context.

So di kursi literally is just at/on the seat. In natural English, on the seat is the best translation here, because crumbs rest on the surface of the seat.

This is very common in Indonesian: di does not always match one single English preposition.

Because the speaker is talking about their own action in a straightforward way:

jadi saya membersihkannya = so I cleaned it/them

That is a normal active sentence.

A passive version is possible, for example:

..., jadi remah roti itu saya bersihkan dengan saputangan.

That would shift focus more toward the thing being cleaned. But the original active version is simpler and very natural.

Yes, saputangan is a normal word meaning handkerchief, though in daily life many people might more often use something like tisu if they mean a tissue.

So the sentence is correct, but depending on the situation, a speaker might also say:

... jadi saya membersihkannya dengan tisu.

That might sound even more everyday in some contexts.

You can do a rough literal breakdown:

• Setelah = after
• makan = eating / eat
• di mobil = in the car
• ada = there were / there are
• remah roti = bread crumbs
• di kursi = on the seat
• jadi = so
• saya = I
• membersihkannya = cleaned it/them
• dengan saputangan = with a handkerchief

A natural English translation would be:

After eating in the car, there were bread crumbs on the seat, so I cleaned them with a handkerchief.

That is better than translating every word mechanically, because natural English and natural Indonesian organize information a little differently.