oneureun deowoseo jeomsime guksureul meokgo sipeoyo.

은 is the topic particle. In 오늘은, it marks today as the topic of the sentence.

So 오늘은 feels like:

• As for today, ...
• Today, ...

It can also add a slight contrast, like today (in particular). For example, it may imply that today is hot, even if other days were not.

If you say just 오늘, the sentence is still understandable, but 오늘은 sounds more natural when setting the scene.

더워서 comes from 덥다 (to be hot) plus -어서, which often means because or so.

So here, 더워서 means:

• because it’s hot
• since it’s hot

It is not 더워요 because this clause is being connected to the next one. The sentence is not ending after hot; it continues into I want to eat noodles.

So the structure is:

• 오늘은 더워서 = Because it’s hot today
• 점심에 국수를 먹고 싶어요 = I want to eat noodles for lunch

This is because 덥다 is a ㅂ-irregular adjective.

The basic dictionary form is 덥다. When you add a vowel-starting ending like -어서, the ㅂ changes to 우:

• 덥다 → 더우-
• 더우 + 어서 → 더워서

This same pattern happens in words like:

• 춥다 → 추워요
• 어렵다 → 어려워요

So 더워서 is the correct irregular form.

Not always. -아서/-어서 can have a few related uses, but one very common use is cause/reason:

• 더워서 = because it’s hot
• 배고파서 = because I’m hungry
• 피곤해서 = because I’m tired

It can also simply connect actions in sequence in some contexts, but in this sentence the meaning is clearly reason:
It’s hot, so I want noodles for lunch.

One useful note: when using -아서/-어서 for a reason, the cause usually comes first and the result comes second.

In this sentence, 점심에 means something like:

• at lunch
• for lunch
• during lunchtime

The particle 에 is often used with times to mean at/on/in.

So:

• 점심에 = at lunch / at lunchtime

In natural English, the best translation may be for lunch, even though the Korean literally looks closer to at lunchtime.

에 is commonly used to mark a time when something happens.

Examples:

• 아침에 = in the morning
• 점심에 = at lunch / at lunchtime
• 저녁에 = in the evening / at dinner time
• 세 시에 = at three o’clock

So 점심에 국수를 먹고 싶어요 literally means
I want to eat noodles at lunchtime.

In English, we often translate that more naturally as I want to eat noodles for lunch.

를 is the object particle. It marks 국수 (noodles) as the thing being eaten.

So:

• 국수 = noodles
• 국수를 = noodles (as the object of the verb)

Because the verb is 먹다 (to eat), the thing you eat usually takes 을/를:

• 밥을 먹어요 = I eat rice / a meal
• 빵을 먹어요 = I eat bread
• 국수를 먹어요 = I eat noodles

In casual speech, Korean speakers sometimes drop 을/를, especially in conversation, but including it is completely normal and clear.

먹고 싶어요 means want to eat.

It is built like this:

• 먹다 = to eat
• 먹고 싶다 = to want to eat
• 먹고 싶어요 = polite form of want to eat

The pattern is:

• verb stem + 고 싶다

Examples:

• 가고 싶어요 = want to go
• 보고 싶어요 = want to see
• 쉬고 싶어요 = want to rest
• 먹고 싶어요 = want to eat

So in this sentence, 국수를 먹고 싶어요 means I want to eat noodles.

Usually, -고 싶어요 is most naturally used for your own wants or in a question about the listener’s wants.

Examples:

• 저는 국수를 먹고 싶어요. = I want to eat noodles.
• 뭐 먹고 싶어요? = What do you want to eat?

For a third person, Korean often prefers a different expression, such as -고 싶어 하다:

• 민수는 국수를 먹고 싶어 해요. = Minsu wants to eat noodles.

That’s because Korean tends to be careful about directly stating another person’s inner feelings or desires.

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

In this sentence, the subject is understood as I because of 먹고 싶어요 (want to eat), which usually expresses the speaker’s desire unless context says otherwise.

So even though 저는 is not written, the meaning is naturally understood as:

• (I) want to eat noodles for lunch because it’s hot today.

If you wanted to be more explicit, you could say:

• 저는 오늘은 더워서 점심에 국수를 먹고 싶어요.

But in normal Korean, leaving out 저는 is very common.

Korean usually follows Subject–Object–Verb, and the verb comes at the end.

This sentence breaks down like this:

• 오늘은 = as for today
• 더워서 = because it’s hot
• 점심에 = at lunch / for lunch
• 국수를 = noodles (object)
• 먹고 싶어요 = want to eat

A very literal order in English would be:

As for today, because it’s hot, at lunch noodles want-to-eat.

That sounds unnatural in English, of course, so the natural English meaning becomes:

Because it’s hot today, I want to eat noodles for lunch.

먹고 싶어요 is in the polite informal style, often called -요 style. It is very common in everyday Korean and is appropriate in many situations.

Compare:

• 먹고 싶어요 = polite, everyday
• 먹고 싶습니다 = more formal
• 먹고 싶어 = casual / intimate

So the whole sentence is polite and natural for normal conversation.

Yes, you could. It would still be understandable and natural.

The difference is that 오늘은 gives a clearer topic feeling, and can add a slight nuance of today in particular.

Compare:

• 오늘은 더워서... = As for today, because it’s hot...
• 오늘 더워서... = Today, because it’s hot...

Both work, but 오늘은 often sounds a little smoother and more complete when introducing the situation.

Yes, a little. 국수 usually refers to noodles, often Korean-style noodles in a general sense.

Depending on the exact dish, Korean might use other words too, such as:

• 라면 = ramen / instant noodles
• 냉면 = cold buckwheat noodles
• 우동 = udon
• 칼국수 = knife-cut noodles

So 국수 is a general noun for noodles, not necessarily one specific dish. In this sentence, it simply expresses noodles as the food the speaker wants.