siganeul akkiryeogo jihacheoreul tayo.

Because 시간 is the object of the verb 아끼다.

• 아끼다 means to save, to spare, or to conserve
• The thing being saved is time
• So Korean uses the object particle -을/를

So:

• 시간을 아끼다 = to save time
• 시간이 would mark time as the subject, which is not what is happening here

In this sentence, there are actually two verbs:

• 시간을 아끼려고 = in order to save time
• 지하철을 타요 = I ride / take the subway

Each verb has its own object.

-려고 expresses intention or purpose. In English, it often corresponds to:

• in order to
• so that
• with the intention of

So:

• 시간을 아끼려고 = in order to save time

The full sentence means that taking the subway is done for that purpose.

A simple pattern is:

• Verb stem + -려고

Examples:

• 돈을 아끼려고 집에서 먹어요. = I eat at home to save money.
• 일찍 가려고 택시를 타요. = I take a taxi to get there early.

Because -려고 attaches to the verb stem, not to the casual/polite conjugated form.

The verb is:

• 아끼다 = to save

Its stem is:

• 아끼-

Then add -려고:

• 아끼 + 려고 → 아끼려고

By contrast:

• 아껴요 is a present-tense polite form
• You do not build -려고 from 아껴요

So the rule is:

• dictionary form: 아끼다
• stem: 아끼-
• purpose form: 아끼려고

In Korean, 타다 is the normal verb for riding or taking a mode of transportation.

So:

• 지하철을 타다 = to take / ride the subway
• 버스를 타다 = to take the bus
• 택시를 타다 = to take a taxi
• 자전거를 타다 = to ride a bicycle

English often uses take for transportation, but Korean uses 타다, whose core meaning is closer to ride/get on.

So even though the English translation may say take the subway, the Korean verb is literally the one used for riding it.

Korean present tense often covers both:

• a habitual action
• a general truth
• a current/future action depending on context

So 지하철을 타요 can mean things like:

• I take the subway
• I’m taking the subway
• I take the subway (when/because...)

Without more context, Korean often leaves that broad and natural.

In this sentence, it most naturally sounds like a habitual or usual action:

• I take the subway to save time

But in the right context, it could also describe a current plan.

Korean very often omits the subject when it is clear from context.

So this sentence does not explicitly say:

• I
• we
• they

It simply says:

• 시간을 아끼려고 지하철을 타요

From the polite ending -아요/어요 and normal conversation context, learners often understand it as:

• I take the subway to save time

But depending on context, it could also mean:

• He/She takes the subway to save time
• We take the subway to save time

Korean relies heavily on context for subjects.

Because there are two different verbs, and each verb has its own object.

Break the sentence into two parts:

1. 시간을 아끼려고

   • verb: 아끼다 = to save
   • object: 시간을 = time

2. 지하철을 타요

   • verb: 타다 = to ride/take
   • object: 지하철을 = the subway

So the sentence contains:

• object of 아끼다
• object of 타다

This is completely normal in Korean when one clause connects to another.

Yes. That would also be natural.

Compare:

• 시간을 아끼려고 지하철을 타요
• 시간을 아끼기 위해서 지하철을 타요

Both mean I take the subway to save time, but there is a slight nuance:

• -려고 is very common and conversational for intention/purpose
• -기 위해서 sounds a bit more formal or explicitly goal-oriented

In everyday speech, -려고 is extremely common and natural here.

Yes, to some extent. Korean word order is flexible as long as the grammar markers make the roles clear.

The most neutral order is:

• 시간을 아끼려고 지하철을 타요.

But you may also hear:

• 지하철을 타요, 시간을 아끼려고.

That can work in speech, but it feels more like the speaker adds the reason afterward.

For learners, the safest and most standard order is:

• reason/purpose + main action

So this sentence is a very typical pattern:

• 시간을 아끼려고 = to save time
• 지하철을 타요 = I take the subway

타요 is in the polite informal style, also called the -아요/어요 style.

It is very common in everyday Korean and is appropriate in many situations:

• talking to someone you do not know well
• speaking politely in daily conversation
• speaking to coworkers, classmates, service workers, etc.

The verb forms would be:

• 타다 = dictionary form
• 타요 = polite everyday form
• 탑니다 = more formal/polite style

So this sentence could also be made more formal as:

• 시간을 아끼려고 지하철을 탑니다.

아끼다 has a few related meanings, and that can be confusing for learners.

Common meanings include:

• to save / conserve

  • 시간을 아끼다 = save time
  • 돈을 아끼다 = save money

• to spare / use carefully

  • 힘을 아끼다 = conserve one’s energy

• to cherish / treasure

  • 가족을 아끼다 = cherish one’s family

In this sentence, the meaning is clearly to save or to conserve time.