Jangan buka jendela kalau angin malam terlalu kencang.

Jangan is used to make a negative command, so it means don’t.

• Jangan buka jendela = Don’t open the window
• It is different from tidak, which is usually used to negate statements:
  • Saya tidak buka jendela = I do not open the window
  • Jangan buka jendela = Don’t open the window

So here, jangan tells someone not to do something.

In Indonesian, commands often use the bare root verb.

• buka = open
• membuka = to open / opens / is opening, in a normal active clause

So:

• Buka jendela! = Open the window!
• Jangan buka jendela! = Don’t open the window!

Using membuka after jangan is usually not the normal choice in everyday Indonesian. The root form sounds more natural in commands and prohibitions.

Indonesian often leaves out the subject when it is already obvious from context, especially in commands.

So Jangan buka jendela naturally means:

• Don’t open the window
• literally, it does not need to say you

You could add kamu or another pronoun, but it is usually unnecessary:

• Jangan buka jendela = natural
• Kamu jangan buka jendela = adds emphasis, like You, don’t open the window

Indonesian often does not use a verb like is/are before adjectives.

So:

• angin malam terlalu kencang
• literally: night wind too strong

This is completely normal Indonesian. The idea of is is understood automatically.

Compare:

• Cuacanya dingin = The weather is cold
• Dia marah = He/She is angry
• Angin malam terlalu kencang = The night wind is too strong

By itself, jendela can mean window, a window, or the window depending on context.

Indonesian does not normally use articles like a or the, so the listener figures it out from the situation.

Also, Indonesian nouns do not have to change form for plural:

• jendela can sometimes mean window or windows
• jendela-jendela makes the plural explicit, but it is only used when needed

In this sentence, jendela most naturally means the window or a window, depending on the situation.

Here kalau means if.

So:

• kalau angin malam terlalu kencang = if the night wind is too strong

Kalau and jika can both mean if, but they are a little different in tone:

• kalau = very common, everyday, natural in speech
• jika = more formal, more common in writing or formal language

So this sentence sounds natural and conversational with kalau.

Yes. Indonesian allows both orders.

You can say:

• Jangan buka jendela kalau angin malam terlalu kencang.
• Kalau angin malam terlalu kencang, jangan buka jendela.

Both are correct. The difference is mostly about focus and style:

• putting Jangan buka jendela first emphasizes the warning first
• putting the kalau clause first emphasizes the condition first

In Indonesian, the main noun usually comes first, and the word that describes it comes after.

So:

• angin malam = night wind
• literally: wind of night or night wind

This is a very common Indonesian pattern:

• rumah besar = big house
• air panas = hot water
• angin malam = night wind

So angin is the main noun, and malam tells you what kind of wind it is.

Terlalu means too or excessively, and kencang here means strong.

So:

• terlalu kencang = too strong

This is important because terlalu is not the same as very:

• sangat kencang = very strong
• kencang sekali = very strong
• terlalu kencang = too strong, stronger than is desirable or safe

So the sentence is not just describing the wind. It suggests the wind is stronger than it should be for opening the window.

No. Kencang has several related meanings depending on context.

It can mean things like:

• strong for wind
• fast for speed
• tight for physical tightness
• hard or forceful in some situations

Examples:

• anginnya kencang = the wind is strong
• mobilnya melaju kencang = the car is going fast
• ikatannya terlalu kencang = the tie/binding is too tight

So in this sentence, because it is talking about angin, the natural meaning is strong.

It is fairly neutral and normal. Jangan buka jendela is a direct prohibition, but not automatically rude.

Whether it sounds strong or gentle depends on context, tone of voice, and relationship.

If you want to make it softer, Indonesian often adds words like these:

• ya
• dong
• deh
• sebaiknya

For example:

• Jangan buka jendela ya kalau angin malam terlalu kencang.
  = a softer, friendly warning
• Sebaiknya jangan buka jendela kalau angin malam terlalu kencang.
  = It’s better not to open the window if the night wind is too strong

So the original sentence is perfectly fine, but it is fairly direct.

Yes, sometimes angin malam can refer more loosely to the night air or the night breeze, depending on context.

Even though angin literally means wind, in natural usage it can sometimes refer to moving air more generally.

So in this sentence, the exact English wording might vary a little depending on context:

• night wind
• night breeze
• night air

But grammatically, the Indonesian structure stays the same.