biga ogi jeone changmuneul dadayagessda.

-기 전에 means before doing something.

So:

• 오다 = to come
• 오기 = coming / the act of coming
• 전에 = before

Together, 오기 전에 means before it comes.
In this sentence, 비가 오기 전에 means before it rains or more literally before rain comes.

Korean often uses verb stem + -기 전에 where English would use before + subject + verb.

Examples:

• 먹기 전에 손을 씻어요. = Wash your hands before eating.
• 자기 전에 책을 읽어요. = I read a book before sleeping.

Because 전에 does not normally attach directly to the dictionary form 오다 in this structure.

To say before doing X, Korean usually changes the verb into a noun-like form with -기, then adds 전에:

• 오다 → 오기
• 가기
• 먹기
• 닫기

So:

• 비가 오기 전에 = before it rains
• 집에 가기 전에 = before going home

This is a very common pattern, and it is something English speakers often need to get used to, because Korean uses a nominalized verb here.

가 is the subject marker here.

In 비가 오다, the thing that is coming is rain, so 비 is the subject:

• 비가 오다 = it rains / rain comes

Korean says rain comes, while English usually says it rains.
That is why 비 gets the subject particle 가.

You will see this same pattern often:

• 눈이 와요. = It snows.
  Literally: snow comes
• 비가 와요. = It rains.
  Literally: rain comes

을 is the object marker.

The verb 닫다 means to close, so the thing being closed is the object:

• 창문을 닫다 = to close the window

So in this sentence:

• 창문을 = the window
• 닫아야겠다 = I should close it / I’d better close it

Together: 창문을 닫아야겠다 = I should close the window.

닫아야겠다 is made from:

• 닫다 = to close
• -아/어야 하다 = have to / must / should
• -겠- = often adds the speaker’s judgment, intention, or realization

So 닫아야겠다 does not just mean a plain, mechanical must close.
It often sounds like:

• I should close it
• I’d better close it
• Looks like I need to close it

There is a sense that the speaker is realizing this or deciding it on the spot.

Both can express necessity, but the nuance is different.

• 닫아야 한다 = have to close / must close
  More neutral, plain, sometimes more objective.
• 닫아야겠다 = I should close it / I’d better close it
  More personal, often the speaker’s immediate judgment or decision.

In this sentence, 닫아야겠다 sounds natural because the speaker notices the situation and thinks, Before it rains, I’d better close the window.

So:

• 닫아야 한다 can sound more like a general statement of obligation.
• 닫아야겠다 often sounds more like a spontaneous conclusion.

Korean often leaves out subjects when they are obvious from context.

In 창문을 닫아야겠다, the subject is not stated, but it is usually understood as I.

That is because -아야겠다 often expresses the speaker’s own thought or decision:

• I should close the window
• I’d better close the window

If you wanted to make the subject explicit, you could say:

• 제가 창문을 닫아야겠어요.

But in everyday Korean, leaving it out is very normal.

Because 비가 오다 is the normal Korean expression for to rain.

Literally, it looks like:

• rain comes

But idiomatically, it means:

• it rains

So 비가 오기 전에 is literally before rain comes, but natural English is before it rains.

This is a good example of why word-for-word translation is not always the most natural way to understand Korean.

Usually it sounds more like a personal judgment than a strict external obligation.

It often suggests:

• the speaker has just noticed something
• the speaker thinks this is the right thing to do
• the speaker is deciding to act

So 비가 오기 전에 창문을 닫아야겠다 feels like:

• I should close the window before it rains.
• I’d better close the window before it rains.

It is not as harsh or forceful as some English uses of must.

Normally, without more context, it sounds like the speaker is the one who should do it.

That is because -아야겠다 strongly suggests the speaker’s own realization or intention.

If you wanted to say that someone else should close it, Korean would usually make that clearer, for example:

• 민수가 창문을 닫아야겠다.
  = Minsu should close the window.
  But even this can sound a bit unusual unless the speaker is making a judgment about Minsu.

More natural alternatives for other people’s obligation are often things like:

• 민수가 창문을 닫아야 해요.
• 민수는 창문을 닫아야 합니다.

It can be broken down like this:

1. 닫다 = to close
2. Verb stem: 닫-
3. Add -아야 하다 → 닫아야 하다 = have to close / should close
4. Add -겠- → 닫아야겠다

So the full form is basically:

• 닫아야 하겠다

In everyday speech, this becomes:

• 닫아야겠다

This is very common in Korean: forms get shortened in natural usage.

Because Korean does not always use a separate future form where English might.

비가 오기 전에 already means the rain is in the future relative to the closing action.
The sequence of events is clear from 전에:

• first: close the window
• later: rain comes

So Korean does not need an extra future marker here.

The sentence naturally communicates: Before the rain comes later, I should close the window now.

The sentence you were given ends in -다, which is plain style and often used in writing, self-talk, or casual narration.

A more polite version would be:

• 비가 오기 전에 창문을 닫아야겠어요.

This sounds like:

• I should close the window before it rains.
• I’d better close the window before it rains.

You could also hear:

• 비가 오기 전에 창문을 닫아야겠네요.

This adds a slight sense of realization, like:

• Looks like I should close the window before it rains.

Yes, it is very natural.

It sounds like a normal thought someone might have after noticing the weather:

• 비가 오기 전에 창문을 닫아야겠다.

It has a very everyday Korean feel because:

• 비가 오기 전에 is a common time expression
• 창문을 닫다 is a basic, natural verb-object combination
• -아야겠다 fits a spontaneous personal decision very well

So this is a good sentence to study because it contains several very common Korean patterns.