Nakasara ang bintana sa kusina dahil malakas ang hangin.

Filipino very often uses predicate-first word order.

So instead of starting with the subject/topic the way English usually does, it often starts with the description or state:

• Nakasara ang bintana. = The window is closed.
• Literally, this is more like Closed the window in terms of word order, though that is not how you should translate it.

Here:

• Nakasara = the predicate/state
• ang bintana = the topic, roughly the window

This word order is completely normal in Filipino.

Nakasara describes a state: something is closed.

It comes from the root sara, which is related to closing/shutting.
The prefix naka- often helps form a word meaning something is in a certain condition or state.

So:

• nakasara = closed, in a closed state

In this sentence, it does not mean is closing or closed it. It means the window is already shut.

A useful comparison:

• Nakasara ang bintana. = The window is closed.
• Isinara ang bintana. = The window was closed / Someone closed the window.

So nakasara focuses on the resulting condition, not the action itself.

Ang is a marker that often points to the topic of the sentence.

In this sentence:

• ang bintana = the window

It marks bintana as the thing being talked about.

A rough way to think about it is:

• Nakasara = what is being said
• ang bintana = what that statement is about

English does not have a direct equivalent of ang, so learners often need time to get used to it.

Sa is a very common marker for location, direction, or sometimes a more general relation like in, at, to, or on, depending on context.

Here:

• sa kusina = in the kitchen

So bintana sa kusina means the window in the kitchen.

In this sentence, sa kusina most naturally describes which window we mean: the one located in the kitchen.

In this sentence, the most natural reading is that it describes the window:

• ang bintana sa kusina = the window in the kitchen

So the sentence means that the kitchen window is closed.

Because Filipino can be flexible, context matters, but without extra context, that is the normal interpretation.

If you wanted to be extra clear in English, you would probably translate it as:

• The window in the kitchen is closed because the wind is strong.

Filipino often does not use an overt verb like English is/are in simple descriptive sentences.

So:

• Nakasara ang bintana. literally has no separate word for is
• but it naturally means The window is closed

The same pattern appears in many Filipino sentences:

• Malaki ang bahay. = The house is big.
• Mainit ang kape. = The coffee is hot.
• Malakas ang hangin. = The wind is strong.

So the missing is is not missing at all from a Filipino point of view; the sentence is complete as it is.

Dahil means because.

It introduces the reason:

• dahil malakas ang hangin = because the wind is strong

So the sentence has:

• main statement: Nakasara ang bintana sa kusina
• reason clause: dahil malakas ang hangin

You can also move the reason clause:

• Dahil malakas ang hangin, nakasara ang bintana sa kusina.

That still means the same thing: Because the wind is strong, the window in the kitchen is closed.

Because malakas is the natural word for strong in this context.

• malakas = strong
• malaki = big/large

In Filipino, wind is commonly described as malakas:

• Malakas ang hangin. = The wind is strong.

Using malaki with hangin would sound unnatural, because wind is not normally described as big.

So this is partly a vocabulary/collocation issue: Filipino speakers naturally say malakas ang hangin, just as English speakers naturally say strong wind.

Because malakas ang hangin is its own clause, with its own predicate-and-topic structure.

Inside that clause:

• malakas = predicate
• ang hangin = topic

So the whole sentence contains two predicate-type parts:

1. Nakasara ang bintana sa kusina
2. malakas ang hangin

joined by dahil.

That is why you see ang twice: each clause has its own topic.

Yes. Sarado is also very common and natural.

• Sarado ang bintana sa kusina.
• Nakasara ang bintana sa kusina.

Both can mean The window in the kitchen is closed.

A small difference in feel:

• sarado is a straightforward adjective-like word meaning closed/shut
• nakasara often emphasizes the state of having been closed

In everyday speech, both are common, and either one would usually be understood perfectly.

By itself, bintana can refer to window or windows, depending on context, because Filipino nouns do not usually change form for plural the way English nouns do.

Here, it is understood as singular because of the meaning/context:

• ang bintana sa kusina = the window in the kitchen

If you wanted to make it clearly plural, you could say:

• ang mga bintana = the windows

So:

• Nakasara ang mga bintana sa kusina. = The windows in the kitchen are closed.

Yes, often it can.

• dahil = because
• kasi = also because, but usually more conversational and informal

So you could say:

• Nakasara ang bintana sa kusina dahil malakas ang hangin.
• Nakasara ang bintana sa kusina kasi malakas ang hangin.

Both are natural.
Dahil can sound a bit more neutral or formal, while kasi is very common in everyday speech.

Yes:

• Nakasara = closed; in a closed state
• ang = topic marker
• bintana = window
• sa = in/at
• kusina = kitchen
• dahil = because
• malakas = strong
• ang = topic marker
• hangin = wind

So the structure is roughly:

• [Closed] [the window in the kitchen] [because] [strong the wind]

But the natural English meaning is:

• The window in the kitchen is closed because the wind is strong.