Kalau talang tersumbat, air hujan bisa meluap ke teras.

Kalau means if in this sentence.

So:

• Kalau talang tersumbat = If the gutter is clogged

In everyday Indonesian, kalau is very common in speech and writing. A slightly more formal alternative is jika.

Examples:

• Kalau hujan, saya di rumah. = If it rains, I stay at home.
• Jika hujan, acara dibatalkan. = If it rains, the event is canceled.

Yes. Talang here means a gutter or a channel that carries rainwater away from the roof.

Depending on context, talang can refer to:

• a roof gutter
• a water channel
• sometimes a trough-like structure

In this sentence, because it is connected with air hujan and overflow, gutter is the most natural translation.

Tersumbat means blocked, clogged, or obstructed.

The base idea is sumbat, which is related to blocking or plugging something.
With the prefix ter-, tersumbat often describes a state or condition:

• saluran tersumbat = a blocked drain
• hidung tersumbat = a blocked nose
• talang tersumbat = a clogged gutter

So tersumbat here is functioning like an adjective: it describes the condition of the gutter.

It can be helpful to think of it as describing a resulting state rather than a normal active verb.

In many cases, ter- can indicate:

1. a state or condition
2. something accidental
3. something already happened / not done deliberately

Here, talang tersumbat is best understood as:

• the gutter is clogged
• the gutter has become blocked

So while it may feel somewhat passive in English, for a learner it is usually easiest to treat tersumbat here as a condition adjective-like form.

Air hujan literally means rain water.

Indonesian often uses noun combinations like this:

• air hujan = rainwater
• air laut = seawater
• air panas = hot water

If the sentence only said hujan bisa meluap, that would sound odd, because rain itself is not usually described as overflowing in the same way. What overflows is the water.

So:

• air hujan bisa meluap = rainwater can overflow

Here bisa means can or may / might, depending on how natural you want the English to sound.

So:

• air hujan bisa meluap ke teras = rainwater can overflow onto the terrace
• or rainwater may overflow onto the terrace

In Indonesian, bisa often expresses possibility or ability. In this sentence, it expresses possibility:

• If the gutter is clogged, overflow is possible.

Meluap means to overflow.

It is used when liquid rises too high and spills out beyond its normal limit.

Examples:

• Sungai itu meluap. = The river overflowed.
• Air meluap dari ember. = The water overflowed from the bucket.

In your sentence:

• air hujan bisa meluap ke teras = the rainwater can overflow onto the terrace

Ke means to or toward.

So:

• meluap ke teras = overflow to / onto the terrace

Indonesian often uses ke for movement in the direction of a place:

• pergi ke pasar = go to the market
• jatuh ke lantai = fall to the floor
• air masuk ke rumah = water enters the house

In English, onto the terrace may sound more natural, but Indonesian simply uses ke teras.

Teras usually means the area at the front or outside part of a house, often something like a:

• porch
• veranda
• terrace
• sometimes patio, depending on the house

The best English word depends on the context and the kind of building. In many everyday Indonesian house-related sentences, teras often feels closer to porch or front terrace.

Indonesian does not normally use articles like a, an, or the.

So:

• talang can mean a gutter or the gutter
• teras can mean a terrace or the terrace

You figure it out from context.

That is very normal in Indonesian. The language usually leaves definiteness unstated unless it really needs to be made clear.

Yes. You can also say:

Air hujan bisa meluap ke teras kalau talang tersumbat.

This means the same thing:

• Rainwater can overflow onto the terrace if the gutter is clogged.

Both orders are natural:

1. Kalau talang tersumbat, air hujan bisa meluap ke teras.
2. Air hujan bisa meluap ke teras kalau talang tersumbat.

The first version puts the condition first, which is very common.

The comma separates the if-clause from the main clause.

Structure:

• Kalau talang tersumbat, = If the gutter is clogged,
• air hujan bisa meluap ke teras. = rainwater can overflow onto the terrace.

This is similar to English, where a comma is often used after an opening if-clause:

• If the gutter is clogged, rainwater can overflow onto the terrace.

If the kalau clause comes second, the comma is usually not needed:

• Air hujan bisa meluap ke teras kalau talang tersumbat.

Yes.

You can say:

• Jika talang tersumbat, air hujan bisa meluap ke teras.

This means the same thing.

The difference is mostly in tone:

• kalau = more everyday, conversational
• jika = a bit more formal or neutral in written language

Both are correct.

Yes, because bisa adds the idea of possibility.

Compare:

• Air hujan meluap ke teras.
  = The rainwater overflows onto the terrace.
  This sounds more like it actually happens.

• Air hujan bisa meluap ke teras.
  = The rainwater can/may overflow onto the terrace.
  This means it is a possible result.

In your sentence, the speaker is explaining a risk or consequence, so bisa is very natural.

It sounds like clear, natural everyday Indonesian, but it is also perfectly acceptable in neutral written language.

Nothing in it is slang. Words like:

• kalau
• talang
• tersumbat
• air hujan
• meluap
• teras

are all standard Indonesian.

So this sentence could easily appear in:

• conversation
• home maintenance advice
• safety instructions
• practical writing about houses or rainwater drainage