achimbabeul meogeoseo deundeunhaeyo.

아침밥 means breakfast. Literally, it is morning meal/rice:

• 아침 = morning
• 밥 = cooked rice, but very often also a meal

So in this sentence, 아침밥 does not necessarily mean the person ate rice. It just means they ate breakfast.

Not necessarily. This is a very common point for learners.

Although 밥 literally means cooked rice, Korean often uses it more broadly to mean a meal. So:

• 밥 먹다 = to eat a meal
• 아침밥 = breakfast
• 점심밥 = lunch meal
• 저녁밥 = dinner meal

So the sentence is about having breakfast, not specifically about eating rice.

을 is the object marker. It marks 아침밥 as the thing being eaten.

So:

• 아침밥을 = breakfast + object marker
• 먹어서 = because I ate / having eaten

Together, 아침밥을 먹어서 means because I ate breakfast.

In casual speech, the object marker is often dropped, so 아침밥 먹어서 든든해요 is also very natural.

Because -아서/어서 here shows a reason or cause.

• 먹어서 든든해요 = I feel satisfied/solid because I ate
• 먹고 든든해요 sounds more like simple sequence: I ate, and I feel satisfied

In this sentence, the speaker is connecting the breakfast directly to the feeling, so 먹어서 is the more natural choice.

It can sometimes feel like either in English, but here it is mainly because.

So the sense is:

• Because I ate breakfast, I feel 든든해요

English might also say After eating breakfast, I feel nice and full, but the Korean here is focusing on the resulting reason more than just the order of events.

든든해요 is a little broader than just I’m full.

It can mean something like:

• I feel pleasantly full
• I feel satisfied
• I feel solid / well-fed
• I feel reassured / ready to go

After eating, 든든하다 often suggests a good, steady feeling of being nourished and comfortable, not just having a stuffed stomach.

This is a very useful distinction.

• 배불러요 = I’m full
  This focuses on your stomach being full.

• 든든해요 = I feel well-fed / satisfyingly full / fortified
  This feels more positive and stable, like the meal gave you energy or comfort.

So after breakfast, 든든해요 often sounds more natural if you mean:

• I feel good and ready for the day
• That breakfast really held me over

Yes, the subject is usually understood from context.

Korean often leaves out subjects when they are obvious. So this sentence naturally implies something like:

• I ate breakfast, so I feel satisfied
• or Since I had breakfast, I feel good and full

If needed, you could add 저는 for clarity:

• 저는 아침밥을 먹어서 든든해요.

But in normal conversation, leaving it out is very common.

-해요 is the polite, everyday speech style.

The base form is:

• 든든하다 = to be satisfying / substantial / reassuring

In polite present tense, it becomes:

• 든든해요

This is a very common style for daily conversation: polite, but not overly formal.

Yes, you can.

In everyday Korean, 아침 can stand for breakfast, so:

• 아침을 먹어서 든든해요
• 아침 먹어서 든든해요

are both natural.

Compared with that:

• 아침밥을 먹어서 든든해요

sounds a bit more explicit or a bit more like breakfast meal. All of these are understandable and natural in the right context.