jeongisereul akkineura bameneun seonpunggiman kyeo.

전기세 means electricity bill or electricity cost.

A very similar and more formal expression is 전기 요금. In everyday speech, many people say 전기세, even though -세 originally means tax. So in real conversation:

• 전기세 = common, casual
• 전기 요금 = a bit more standard/formal

In this sentence, 전기세를 아끼다 means to save on the electricity bill / reduce electricity costs.

아끼느라 comes from 아끼다 (to save, to spare, to be frugal with) + -느라.

So 전기세를 아끼느라 means something like:

• because I’m trying to save on electricity
• in order to save on the electricity bill
• while focusing on saving electricity costs

The important nuance of -느라 is that it often shows that one action is the reason for another situation, especially when there is some trade-off, inconvenience, or limitation.

So this sentence has the feeling of:

• Because I’m trying to save on the electricity bill, I only turn on the fan at night.

Great question. Both can relate to purpose, but the nuance is different.

• -려고 = in order to, often just showing intention or purpose
• -느라 = because I’m busy/focused doing this, often implying a result, trade-off, or inconvenience

Compare the feeling:

• 전기세를 아끼려고 밤에는 선풍기만 켜.
  = I only turn on the fan at night in order to save on electricity.
  This is neutral and straightforward.

• 전기세를 아끼느라 밤에는 선풍기만 켜.
  = Because I’m trying to save on electricity, I only turn on the fan at night.
  This sounds more like I’m doing this as a compromise.

So -느라 gives a stronger sense of this is the reason I have to do things this way.

Because -느라 attaches to the verb stem.

The verb is 아끼다.
Its stem is 아끼-.

So:

• 아끼다 → 아끼느라

You do not use the -아/어 form before -느라.

Compare:

• 먹다 → 먹느라
• 공부하다 → 공부하느라
• 아끼다 → 아끼느라

를 is the object marker. It marks 전기세 as the thing being saved/reduced.

So:

• 전기세를 아끼다 = to save on the electricity bill

In English, we might say save electricity or save on the electric bill, but Korean uses the object marker to show what the action is affecting.

밤에 just means at night.

밤에는 is 밤에 + 는, where 는 adds topic/contrast nuance. It often sounds like:

• at night, at least...
• as for nighttime...
• when it comes to nighttime...

So 밤에는 선풍기만 켜 suggests a contrast, either stated or unstated. For example:

• maybe during the day something different happens
• maybe at night the speaker is especially careful
• maybe the speaker is contrasting night with other times

So:

• 밤에 선풍기만 켜 = simply I only turn on the fan at night
• 밤에는 선풍기만 켜 = At night, I only turn on the fan with a mild contrastive feeling

만 means only.

So:

• 선풍기 = fan
• 선풍기만 = only the fan

This means the speaker turns on the fan, and not other things that might use more electricity, such as an air conditioner.

Examples of 만:

• 물만 마셔. = I only drink water.
• 주말에만 쉬어요. = I rest only on weekends.
• 선풍기만 켜. = I only turn on the fan.

Normally, yes:

• 선풍기를 켜 = turn on the fan

But when 만 is added, the particle often replaces or makes the object marker unnecessary in everyday speech:

• 선풍기만 켜 = I only turn on the fan

This is very natural.

You could also technically see forms like 선풍기만을, but in normal conversation 선풍기만 켜 is much more common and natural.

So here:

• 전기세를 = object marked normally
• 선풍기만 = 만 is doing the main particle job

켜 comes from the verb 켜다, which means to turn on something like a light, TV, computer, fan, etc.

So:

• 켜다 = dictionary form
• 켜 = casual present style
• 켜요 = polite present style

Examples:

• 불을 켜. = Turn on the light.
• 에어컨을 켜요. = I turn on the air conditioner.
• 선풍기만 켜. = I only turn on the fan.

Yes, 켜 here is a casual present-tense form. In Korean, the simple present can express:

• a habitual action
• a general practice
• something you do in that situation

So 밤에는 선풍기만 켜 most naturally means:

• At night, I only turn on the fan
• At night, I just use the fan

It is not necessarily describing the exact moment right now. It sounds more like a habit or usual behavior.

If you wanted to emphasize an action happening right now, you might use 켜고 있어, but that would change the meaning:

• 지금 선풍기를 켜고 있어. = I’m turning on / I have on the fan right now.

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

So the sentence could imply:

• I only turn on the fan at night
• we only turn on the fan at night
• sometimes even a general people do this

But in most everyday contexts, it will be understood as I.

A fuller version could be:

• 저는 전기세를 아끼느라 밤에는 선풍기만 켜요.

But Korean usually leaves out 저는 if it is already obvious.

Yes, -느라 often carries a nuance of effort, preoccupation, or trade-off, and it frequently appears in situations that are inconvenient, limiting, or somewhat negative.

In this sentence, it suggests something like:

• Because I’m trying to save money on electricity, I have to settle for just the fan at night.

So it is not strongly negative, but it does sound like a compromise.

That is why this sentence feels a bit different from a more neutral purpose sentence with -려고.

The polite version is:

• 전기세를 아끼느라 밤에는 선풍기만 켜요.

Changes:

• 켜 → 켜요

Everything else can stay the same.

If you want an even more formal or slightly more standard version, you might also say:

• 전기 요금을 아끼느라 밤에는 선풍기만 켜요.

Yes, that is a very natural English translation.

Even though 켜다 literally means to turn on, in context English often prefers:

• I only use a fan at night
• At night, I just use the fan
• To save on electricity, I only turn on the fan at night

All of these capture the meaning well. The Korean specifically says turn on the fan only, but natural English may phrase it more broadly as use only a fan.