Learn Hardcore Indonesian: Teman saya sudah cukup mahir menjelaskan tatabahasa dalam bahasa Indonesia dan Inggris. - My friend is already quite skilled at explaining grammar in Indonesian and English.

Putting the pronoun after the noun is the standard pattern for possession.
Saya teman would be interpreted as something like “I (am) a friend” (and even that would usually just be saya teman in context, not as a fixed phrase for “my friend”).

So to say my X, you generally use X + pronoun, not pronoun + X.

Does teman saya mean my friend (one person) or my friends (more than one)?

On its own, teman saya is number-neutral. It can mean:

my friend (one)
my friends (more than one)

Indonesian often doesn’t mark plural nouns unless it’s important. Context usually tells you whether it’s singular or plural.

If you really want to be clear:

teman saya – my friend / my friends (neutral)
seorang teman saya – one (a) friend of mine
teman-teman saya – my friends (definitely plural)

What is the difference between saya and aku here? Could I say Teman aku?

Both saya and aku mean I / me, but they differ in formality:

saya – neutral / polite, safe in almost any situation
aku – informal, used with close friends, family, or in casual contexts

So:

teman saya – my friend (neutral/polite)
teman aku – my friend (more casual/intimate)

In written examples or teaching materials, saya is more common because it’s broadly appropriate. Grammatically, Teman aku sudah cukup mahir… is fine; it just sounds more casual.

What does sudah do in sudah cukup mahir?

Sudah is an aspect marker that usually means already. It indicates that a state has been reached.

dia mahir – he/she is skilled
dia sudah mahir – he/she is already skilled (wasn’t before, but now is)

In Teman saya sudah cukup mahir…, sudah suggests some progress or change over time. It implies that:

previously your friend was less skilled,
but now they have reached a level that is quite skilled.

So a good natural translation is:
My friend is already quite proficient at…

What exactly does cukup mean in cukup mahir? Is it “enough” or “quite”?

Cukup has two main related meanings:

enough / sufficient (quantitative)
- uang saya cukup – my money is enough
- cukup waktu – enough time
quite / fairly / rather (degree of quality)
- cukup mahir – quite skilled / fairly proficient
- cukup baik – quite good / fairly good

In sudah cukup mahir, cukup is mainly about degree:
Your friend is skilled to a satisfactory or reasonably high level, though not necessarily at a “very, extremely expert” level.

Compare:

cukup mahir – quite skilled
sangat mahir / sangat mahir sekali – very / extremely skilled

Is the word order sudah cukup mahir fixed? Could I say cukup sudah mahir?

The natural order is:

sudah + (degree adverb) + adjective
sudah cukup mahir

Putting sudah first is normal, and speakers instinctively prefer sudah cukup mahir.

Variants like cukup sudah mahir sound awkward or unnatural. You might sometimes hear sudah mahir sekali, sudah sangat mahir, etc., but sudah tends to come before other degree words like cukup, sangat, sekali.

Why is there no word for is (like to be) in this sentence?

Indonesian normally does not use a verb like “to be” (is/are/am) before adjectives.

So instead of:

(He is busy.) → Dia sibuk. (literally: he busy)
(This is difficult.) → Ini sulit. (this difficult)

Similarly:

Teman saya sudah cukup mahir…
literally: My friend already quite skilled…

You do not say:

Teman saya adalah sudah cukup mahir… – this is ungrammatical.

The word adalah exists but is used mainly before nouns or noun phrases in more formal contexts, not before adjectives like mahir in this kind of sentence.

What does mahir mean exactly? How is it different from pintar or pandai?

Mahir means skilled, proficient, adept and often implies practical ability.

mahir menjelaskan – skilled at explaining
mahir bermain gitar – good at playing guitar
mahir menggunakan komputer – proficient at using a computer

Pintar and pandai more generally mean clever / smart / good at something, and can sound a bit broader or more about intelligence:

pintar matematika – good at math
pandai memasak – good at cooking

You could say teman saya pintar menjelaskan tatabahasa, but mahir is slightly more technical/professional sounding, especially with skills like explaining grammar. It fits well with the idea of proficiency.

Why is it menjelaskan and not something like menjelas or just jelas?

The base word is jelas = clear (adjective).

To say to explain / to make something clear, Indonesian uses a me-…-kan verb:

jelas (clear) → menjelaskan (to explain, to clarify)

There is no verb menjelas in standard Indonesian.

Examples:

Guru itu menjelaskan pelajaran. – The teacher explains the lesson.
Bisa tolong menjelaskan lagi? – Could you explain again?

So in mahir menjelaskan tatabahasa, menjelaskan is the correct verb form meaning to explain (something).

Why is there no preposition like untuk before menjelaskan? Why mahir menjelaskan, not mahir untuk menjelaskan?

In Indonesian, adjectives of ability or skill are often followed directly by a verb, without a preposition:

mahir menjelaskan – skilled at explaining
pintar memasak – good at cooking
pandai bernyanyi – good at singing

So mahir menjelaskan tatabahasa is completely natural.

Using untuk (mahir untuk menjelaskan) is not needed and sounds off. The pattern is simply:

[adjective of skill] + [verb]
mahir + menjelaskan

Is tatabahasa correct, or should it be tata bahasa?

In Indonesian, the more standard spelling is:

tata bahasa (two words) – grammar

In Malay, you very commonly see:

tatabahasa (one word)

In practice:

In Indonesia, you’ll mostly see tata bahasa in formal writing, dictionaries, textbooks.
You might still encounter tatabahasa in some Indonesian contexts, and speakers will understand it, but tata bahasa is the form that follows current Indonesian spelling conventions.

So for Indonesian learners, it’s safer to write:

tata bahasa = grammar

Why is it dalam bahasa Indonesia dan Inggris and not di bahasa Indonesia dan Inggris?

Both dalam and di can translate as in, but they’re used differently.

di – mainly physical location:
- di rumah – in/at home
- di sekolah – at school
dalam – in, inside / within / in terms of, often more abstract:
- dalam kalimat ini – in this sentence
- dalam bahasa Indonesia – in Indonesian (language)
- dalam bentuk lisan – in spoken form

When talking about “in a language”, Indonesian typically uses:

dalam bahasa X

So:

menjelaskan tatabahasa dalam bahasa Indonesia dan Inggris
= explain grammar in Indonesian and English

Using di bahasa Indonesia here would sound unnatural.

Why is it bahasa Indonesia dan Inggris instead of repeating bahasa before Inggris?

Indonesian allows you to omit repeated words in coordinate structures if the meaning is clear.

So:

bahasa Indonesia dan bahasa Inggris
can be shortened to
bahasa Indonesia dan Inggris

Both mean the Indonesian and English languages.

Some writers prefer to repeat bahasa (bahasa Indonesia dan bahasa Inggris) for maximum clarity or formality, but omitting the second bahasa is very common and perfectly correct.

Is this sentence formal or informal? Could I use it in both spoken and written Indonesian?

The sentence:

Teman saya sudah cukup mahir menjelaskan tatabahasa dalam bahasa Indonesia dan Inggris.

is neutral in tone:

teman saya → neutral (not slangy like temen gue, not very stiff)
vocabulary like mahir, menjelaskan, tata(bahasa), dalam bahasa is standard.

You can use it:

in spoken Indonesian (normal, polite conversation),
in written Indonesian (emails, essays, reports), possibly changing tatabahasa to tata bahasa for formal standards.

It works well in almost any context where you’d want to say “My friend is already quite proficient at explaining grammar in Indonesian and English.”