oneureun deowoseo banpareul ibeoyo.

은 is the topic marker. In 오늘은, the speaker is setting today as the topic, something like:

• As for today...
• Today, ...

So 오늘은 더워서 반팔을 입어요 has the feeling of Today, since it’s hot, I wear short sleeves.

Using 은/는 often adds contrast or emphasis too. Depending on context, it can slightly suggest:

• Today it’s hot
• maybe unlike some other day

But in many everyday sentences, it simply marks the topic naturally.

This is because 덥다 is a ㅂ-irregular adjective.

Here is what happens:

• dictionary form: 덥다 = to be hot
• stem: 덥-
• when a vowel-starting ending like -아서/어서 is attached, the ㅂ changes to 우
• so: 덥 + 어서 → 더워서

This same pattern happens in other common words too:

• 춥다 → 추워요
• 어렵다 → 어려워요

So 더워서 is the correct conjugated form of 덥다 with -어서.

In this sentence, -아서/어서 means because or so.

So:

• 더워서 = because it’s hot
• 오늘은 더워서 반팔을 입어요 = Today, because it’s hot, I wear short sleeves

This ending connects two parts of a sentence:

1. reason/cause
2. result/action

So the structure is:

• 더워서 = because it’s hot
• 반팔을 입어요 = I wear short sleeves

A very natural English gloss is:

• It’s hot today, so I’m wearing short sleeves.

The choice between -아서 and -어서 depends on the vowel before the ending.

A simple rule:

• use -아서 after ㅏ or ㅗ
• use -어서 after most other vowels

But with irregular forms like 덥다 → 더워-, you learn the final result as 더워서.

So even though the dictionary form is 덥다, the actual conjugated form becomes 더워서.

반팔 literally means short sleeve.

In everyday Korean, 반팔 is often used as shorthand for:

• a short-sleeved shirt
• short-sleeved clothing
• wearing short sleeves

So 반팔을 입어요 naturally means:

• I wear a short-sleeved shirt
• I wear short sleeves

Korean often leaves out words that are obvious from context. So 반팔 by itself can stand in for something like:

• 반팔 옷
• 반팔 티셔츠

을/를 is the object marker.

The verb 입다 means to wear, and the thing being worn is the object:

• 반팔을 입어요 = I wear short sleeves
• literally: I wear the short-sleeved item

So:

• 반팔 = object
• 을 = marks it as the object
• 입어요 = wear

Because 반팔 ends in a consonant, it takes 을, not 를.

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

So even though English usually needs I, Korean often does not say it if everyone already knows who is being talked about.

This sentence could be understood as:

• I wear short sleeves today because it’s hot
• or we/people wear short sleeves today because it’s hot

In many real situations, context tells you who the subject is. If needed, you could say:

• 저는 오늘은 더워서 반팔을 입어요 = As for me, I wear short sleeves today because it’s hot

But very often 저는 is unnecessary.

Korean normally follows Subject-Object-Verb order, and the verb usually comes at the end.

So this sentence is organized like this:

• 오늘은 = as for today
• 더워서 = because it’s hot
• 반팔을 = short sleeves / a short-sleeved shirt
• 입어요 = wear

This is very normal Korean sentence structure. English puts the verb earlier, but Korean saves the main verb for the end.

입어요 is in the present polite form.

From the dictionary form:

• 입다 = to wear
• 입어요 = wear / am wearing

In Korean, the present tense can cover both:

• a habitual action: I wear
• an action happening now: I am wearing

So depending on context, 반팔을 입어요 can mean:

• I wear short sleeves
• I’m wearing short sleeves

In this sentence, English often translates it naturally as I’m wearing short sleeves, because it sounds like a current situation.

Good question. Both can be possible, but they are not exactly the same.

• 입어요 can mean wear / am wearing
• 입고 있어요 more explicitly emphasizes the ongoing state of wearing something

So:

• 반팔을 입어요 = natural, simple, everyday
• 반팔을 입고 있어요 = specifically I’m wearing short sleeves right now

Because 입다 already often works well in the present tense for clothing, 입어요 sounds very natural here.

Usually in a sentence like this, yes, but the nuance can also be:

• because it’s hot
• since it’s hot
• it’s hot, so...

So -아서/어서 does not always map to one single English word. It expresses a natural cause-and-result connection.

For this sentence, all of these are reasonable:

• Because it’s hot today, I wear short sleeves.
• It’s hot today, so I’m wearing short sleeves.
• Since it’s hot today, I’m wearing a short-sleeved shirt.

A natural pronunciation is roughly:

• 오느른 더워서 반파를 이버요

A few helpful pronunciation points:

• 오늘은 sounds like 오느른
• 반팔을 sounds close to 반파를
• 입어요 is pronounced close to 이버요

That last one happens because in normal pronunciation, 입어요 is said like 이버요.

So the whole sentence flows smoothly in speech rather than sounding exactly like each written syllable one by one.