Saya lupa menyalakan sein ketika mau belok kanan, jadi Ayah menyuruh saya lebih hati-hati.

Menyalakan is the meN- verb form of nyalakan, and it is the normal dictionary-style active verb in a full sentence.

• menyalakan sein = to turn on the turn signal
• nyalakan sein! = turn on the turn signal! (command)

So in this sentence, menyalakan fits because the speaker is describing an action, not giving an order.

Sein means turn signal, indicator, or blinker in the context of driving.

So:

• menyalakan sein = to turn on the indicator
• lupa menyalakan sein = forgot to use the turn signal

This word is very common in everyday Indonesian, especially in traffic-related speech.

In Indonesian, verbs often follow one another directly without needing a separate word like English to.

So:

• lupa menyalakan sein literally looks like forget turn-on signal
• natural English: forgot to turn on the signal

This is very normal Indonesian structure. Another similar example:

• Saya mau makan = I want to eat

There is no separate word for to before eat.

Indonesian often omits the subject when it is already clear from context.

In this sentence:

• Saya lupa menyalakan sein ketika mau belok kanan
• literally: I forgot to turn on the signal when about to turn right

Even though saya is not repeated before mau belok kanan, it is understood that I am the one who was about to turn right.

A fuller version could be:

• Saya lupa menyalakan sein ketika saya mau belok kanan

But repeating saya is not necessary.

Mau often means want, but in many contexts it also means about to or going to.

Here:

• ketika mau belok kanan = when I was about to turn right

If you translated it as when I wanted to turn right, that could sound possible in English, but here the driving context strongly suggests about to turn right.

All three can often mean when.

In this sentence, ketika sounds natural and slightly more formal or neutral. You could also say:

• saat mau belok kanan
• waktu mau belok kanan

These are all understandable. In casual speech, waktu is very common. Ketika often feels a bit more written or polished.

Jadi can mean different things depending on context.

Here it means so, therefore, or as a result:

• ..., jadi Ayah menyuruh saya lebih hati-hati.
• ..., so Dad told me to be more careful.

In other contexts, jadi can mean become:

• Dia jadi dokter = He became a doctor

So yes, jadi has multiple uses, and here it functions as a connector meaning so.

Ayah means father or dad.

It is capitalized here because it is being used like a name or direct family title, similar to English Dad:

• Ayah menyuruh saya... = Dad told me...

If you were speaking more generally about a father, it might be lowercase:

• ayah saya = my father

Capitalization style can vary, but in many learning materials and writing contexts, family titles used like names are capitalized.

Menyuruh means to tell someone to do something, to order, or to instruct.

In this sentence:

• Ayah menyuruh saya lebih hati-hati
• Dad told me to be more careful

It usually involves a person being told or instructed to do something.

Pattern:

• menyuruh + person + action/state

Examples:

• Ibu menyuruh saya tidur = Mom told me to sleep
• Guru menyuruh murid membaca = The teacher told the students to read

Indonesian usually does not need a verb like English to be in this kind of structure.

So:

• lebih hati-hati = more careful

And:

• Ayah menyuruh saya lebih hati-hati
• literally: Dad told me more careful
• natural English: Dad told me to be more careful

The idea of be is understood from the structure and does not need to be said explicitly.

Hati-hati means careful or be careful.

Lebih means more.

So:

• lebih hati-hati = more careful / more carefully depending on context

In this sentence, it means the father wanted the speaker to act with greater caution.

A useful note: hati-hati can also be used by itself as a warning:

• Hati-hati! = Be careful!

It can function a bit flexibly in Indonesian.

In English, we often separate:

• careful = adjective
• carefully = adverb

But Indonesian often uses hati-hati for both ideas depending on context.

So:

• Dia orang yang hati-hati = He is a careful person
• Dia mengemudi dengan hati-hati = He drives carefully

In your sentence, lebih hati-hati can be understood as more careful in behavior.

In Indonesian, direction expressions are often simpler than in English.

• belok kanan = turn right
• belok kiri = turn left

There is no need for an extra word like to. This is just the normal way to express it.

No, it normally means I forgot to turn on the signal.

If you wanted to say I forgot that I had turned on the signal, you would need a different structure, such as one using bahwa or a clause making that meaning clear.

So:

• lupa + verb usually means forgot to do something

Example:

• Saya lupa membawa dompet = I forgot to bring my wallet

Yes, it sounds natural and clear.

A slightly more casual spoken version might be:

• Aku lupa nyalain sein pas mau belok kanan, jadi Ayah nyuruh aku lebih hati-hati.

Differences:

• saya → aku
• menyalakan → nyalain
• ketika → pas
• menyuruh → nyuruh

Your original sentence is more neutral and suitable for learners, writing, or polite speech.

Yes. Although menyuruh can mean order, in family situations it can also feel like told me, told me to, or instructed me to rather than a harsh command.

So here it likely means the father told the speaker to be more careful after the mistake.

The exact strength depends on tone and context, but told me to be more careful is a good natural interpretation.