Learn Hardcore Indonesian: Kenyamanan kursi dan pencahayaan yang baik membantu saya berkonsentrasi saat belajar. - The comfort of the chair and good lighting help me concentrate when studying.

nyaman → ke
- nyaman + -an → kenyamanan (comfort)
This pattern often makes abstract nouns from adjectives:
- indah (beautiful) → keindahan (beauty)
- penting (important) → kepentingan (interest, importance)

So kenyamanan kursi literally means the comfort of the chair or chair comfort.

What is the difference between kenyamanan kursi and kursi yang nyaman? Could I rewrite the sentence with kursi yang nyaman?

Kenyamanan kursi = the comfort of the chair (focus on the quality or degree of comfort).
Kursi yang nyaman = a comfortable chair (focus on the chair as an object).

You can absolutely rewrite the sentence as:

Kursi yang nyaman dan pencahayaan yang baik membantu saya berkonsentrasi saat belajar.

This sounds a bit more concrete and everyday: Comfortable chairs and good lighting help me concentrate when studying.

The original kenyamanan kursi feels slightly more abstract or formal, as if you’re talking about the general level of comfort.

What exactly does pencahayaan mean, and how is it different from cahaya?

Cahaya = light (the light itself).
Pencahayaan = lighting (the arrangement/condition of light in a place).

Pencahayaan comes from cahaya with the pattern peN- -an:

cahaya → pe
- cahaya + -an → pencahayaan

So:

cahaya matahari = sunlight
pencahayaan di ruangan ini bagus = the lighting in this room is good

In the sentence, pencahayaan yang baik is best understood as good lighting.

Does yang baik describe only pencahayaan, or both kenyamanan kursi and pencahayaan?

Grammatically, yang baik attaches to the closest noun phrase, which is pencahayaan. So the default reading is:

kenyamanan kursi (chair comfort)
pencahayaan yang baik (good lighting)

If you want to clearly say that both the chair comfort and the lighting are good, you could say, for example:

Kenyamanan kursi yang baik dan pencahayaan yang baik membantu saya berkonsentrasi saat belajar.
Or more naturally: Kursi yang nyaman dan pencahayaan yang baik membantu saya berkonsentrasi saat belajar.

In everyday conversation, people might understand that both should be good, but grammatically yang baik is tied to pencahayaan.

Who is the subject of membantu in this sentence? Why is there no pronoun like mereka?

The subject is the whole noun phrase:

Kenyamanan kursi dan pencahayaan yang baik

Indonesian does not require a separate subject pronoun when the subject is already expressed as a noun phrase. Also, verbs like membantu do not change form for singular/plural, so you don’t need anything like they:

Kenyamanan kursi dan pencahayaan yang baik membantu saya …
= The comfort of the chair and good lighting help me …

Adding mereka here would be ungrammatical, because you would be doubling the subject.

Could I say membantu saya untuk berkonsentrasi? Is there any difference from membantu saya berkonsentrasi?

Both are acceptable:

… membantu saya berkonsentrasi …
… membantu saya untuk berkonsentrasi …

Differences:

Without untuk is very common and sounds natural and straightforward.
With untuk can sound slightly more formal or slightly more explicit, but it’s still very normal.

In many sentences with membantu, untuk is optional before another verb:

Kacamata ini membantu saya (untuk) melihat dengan jelas.

So your original version without untuk is perfectly fine.

Why is berkonsentrasi used instead of just konsentrasi?

Berkonsentrasi is the standard verb form meaning to concentrate:

Saya berkonsentrasi. = I concentrate / I’m concentrating.

It uses the ber- prefix that often makes intransitive verbs.

In casual spoken Indonesian, people often say:

Saya harus konsentrasi.

Here konsentrasi is used like a verb in practice, but grammatically berkonsentrasi is the more complete/standard form, especially in written or formal Indonesian.

So in your sentence, berkonsentrasi is the “textbook-correct” choice.

What is the nuance of saat belajar compared with saat saya belajar or ketika saya belajar?

All of these are possible:

saat belajar
saat saya belajar
ketika saya belajar

Differences:

saat belajar = when studying / while studying
- The subject (saya) is understood from context. This is natural and not incomplete.
saat saya belajar = when I study
- Slightly more explicit.
ketika saya belajar
- ketika is a bit more formal or written-sounding than saat, but the meaning is very similar.

In everyday speech and writing, saat belajar and ketika belajar are both common and feel natural.

What’s the difference between saat, ketika, and waktu in this kind of sentence? Can I replace saat with them?

In your sentence, you could say:

… berkonsentrasi saat belajar.
… berkonsentrasi ketika belajar.
… berkonsentrasi waktu belajar. (more informal)

General nuance:

saat – very common and neutral. Possible in both spoken and written Indonesian.
ketika – slightly more formal/literary, often found in writing, but also used in speech.
waktu – literally time. Used like when in more informal or conversational speech:
- Waktu saya belajar, … = When I study, …

So yes, you can usually swap them here, but saat and ketika sound a bit more neutral/formal than waktu.

Does belajar mean to study or to learn?

Belajar can mean both, depending on context:

To study (doing study as an activity):
- Saya belajar setiap malam. = I study every night.
To learn (acquire a skill or knowledge):
- Saya belajar bahasa Indonesia. = I’m learning Indonesian.

In your sentence, saat belajar is closer to when studying or while I’m studying.

What is the difference between membantu and menolong for help? Why is membantu used here?

Both can be translated as to help, but they’re used a bit differently:

membantu – to help in the sense of assist, make something easier, support:
- Kacamata membantu saya melihat. (Glasses help me see.)
- Kopi membantu saya tetap terjaga. (Coffee helps me stay awake.)
menolong – to help in the sense of rescue, save from trouble or danger:
- Dia menolong orang yang tenggelam. (He helped/saved the drowning person.)

In your sentence, kenyamanan kursi dan pencahayaan yang baik membantu saya berkonsentrasi is about making it easier to concentrate, so membantu is the natural choice.

Is there any difference between kursi and bangku for chair?

Yes, there is a nuance:

kursi – chair in general (usually with a backrest, like a standard chair).
bangku – bench or stool (often long or without a backrest, like a simple school bench or a bar stool).

In many contexts, kursi is the default word for “chair.”
So kenyamanan kursi suggests the comfort of a normal chair (e.g., office chair, study chair).

Could we add itu after baik, as in pencahayaan yang baik itu membantu …? What would that change?

Yes, you could say:

Kenyamanan kursi dan pencahayaan yang baik itu membantu saya berkonsentrasi saat belajar.

Adding itu makes the phrase more specific, referring to that particular comfort and lighting, often something already known in the context, for example:

You’re talking about this room, this classroom, that library, etc.

Without itu, the sentence is more general: speaking about comfort and lighting as general factors. With itu, it points more to a specific situation your listener can identify.