Waktu istirahat sudah habis.

• waktu = time
• istirahat = rest, break
• sudah = already
• habis = finished, used up, over

So waktu istirahat means break time or rest time, and sudah habis means is already over / has already run out.

In Indonesian, the head noun often comes first, followed by a word that describes or specifies it.

So:

• waktu istirahat = time for resting / break time
• literally, it is something like rest-time

This is a very common pattern:

• jam makan = mealtime
• uang sekolah = school money / money for school
• ruang tamu = guest room

So waktu istirahat is the natural order.

Sudah marks that something has already happened or is already the case.

In this sentence, it adds the idea of completion:

• Waktu istirahat habis = the break time is over
• Waktu istirahat sudah habis = the break time is already over

In many contexts, sudah makes the sentence sound more natural because it emphasizes that the break has reached its end.

Here habis means finished, over, or used up.

It is a very common Indonesian word and can be used in several related ways:

• Uangnya habis. = The money is gone / used up.
• Makanannya habis. = The food is finished.
• Pelajarannya habis. = The lesson is over/finished.
• Waktu istirahat sudah habis. = Break time is over.

So in this sentence, habis does not mean to spend actively; it describes a state: the break time has run out.

Indonesian often does not use a copula like is / am / are in sentences like this.

English:

• The break time is over.

Indonesian:

• Waktu istirahat sudah habis.

This is normal. Indonesian can put the subject first and then a predicate such as an adjective, noun, or stative verb without needing a separate word for is.

Other examples:

• Dia sakit. = He/She is sick.
• Rumahnya besar. = His/Her house is big.
• Saya guru. = I am a teacher.

It is best understood here as a stative predicate meaning finished / over / gone.

For English speakers, it may feel adjective-like because it describes a state:

• The break time is over.

But in Indonesian grammar, words like habis often behave flexibly. You do not need to force it into only one English-style category to use it correctly.

The important practical point is:

• X sudah habis = X is already finished / used up / over

You might be understood, but Waktu istirahat sudah habis is clearer and more natural if you mean break time is over.

Compare:

• Waktu istirahat sudah habis. = The break time is over.
• Istirahat sudah habis. = The break/rest is over.

The second one is possible in some contexts, but it can sound less complete or less specific. Using waktu istirahat makes it clear that you are talking about the allotted break period.

Yes. Telah and sudah can both mark completion, but they differ in tone.

• sudah = very common in everyday speech
• telah = more formal, more written, less conversational

So:

• Waktu istirahat sudah habis. = natural everyday Indonesian
• Waktu istirahat telah habis. = correct, but more formal

In normal spoken Indonesian, sudah is usually the better choice.

Yes, that is also natural in many contexts.

• waktu istirahat = break time
• jam istirahat = break hour / break period

In real usage, jam istirahat is extremely common for school or work breaks.

So both are possible:

• Waktu istirahat sudah habis.
• Jam istirahat sudah habis.

The exact preference may depend on region, habit, or situation, but both are understandable and natural.

For a question:

• Waktu istirahat sudah habis? = Is break time already over?
• Apakah waktu istirahat sudah habis? = Has break time already ended?

For a negative meaning such as not over yet, Indonesian usually uses belum rather than simply negating sudah:

• Waktu istirahat belum habis. = Break time is not over yet.

This is a very common pattern:

• sudah = already
• belum = not yet

So belum habis is the natural opposite of sudah habis.