baega gopaseo sikdangeseo mandureul jumunhaesseoyo.

That is just the natural Korean way to express hunger.

• 배 = stomach, belly
• 고프다 = to be hungry

So 배가 고프다 literally looks like the stomach is hungry, but it simply means to be hungry.

This is very common in Korean. In English, hunger is described with I am hungry. In Korean, it is often expressed through 배.

Also, 배 can mean other things like pear or boat, but here the context clearly shows it means stomach/belly.

가 is the subject marker, so 배가 고프다 marks 배 as the thing being described: the stomach is hungry.

• 배가 고프다 = the neutral, standard way to say I’m hungry
• 배는 고프다 would put special topic emphasis on as for my stomach, it is hungry

In most normal situations, 배가 고프다 is the natural choice.

It comes from 고프다 + -아서/어서.

Step by step:

• dictionary form: 고프다
• stem: 고프-
• with -아서/어서, the ㅡ drops
• because the earlier vowel is ㅗ, it takes -아서
• so: 고프 + 아서 → 고파서

So 고파서 means because (someone) is hungry or sometimes being hungry, ...

Here, -아서/어서 gives a reason or cause, so 고파서 means because I was hungry.

In this sentence:

• 배가 고파서 = because I was hungry
• 식당에서 만두를 주문했어요 = I ordered dumplings at a restaurant

So the whole sentence means that the hunger is the reason for the ordering.

A useful note: -아서/어서 can also connect events in a sequence, but in this sentence the meaning is clearly cause/reason.

Because 에서 marks the place where an action happens.

• 식당에서 = at/in the restaurant, where the action of ordering took place
• 에 is usually used for destination or location with existence, not the place where an action is performed

Compare:

• 식당에서 먹었어요 = I ate at the restaurant
• 식당에 갔어요 = I went to the restaurant

Since 주문하다 is an action done there, 에서 is correct.

만두 means dumpling(s), and 를 is the object marker.

So 만두를 주문했어요 means ordered dumplings.

• 만두 = dumplings
• 를 = marks 만두 as the thing being ordered

In casual conversation, 를 is sometimes omitted, but in careful standard Korean it is very common to include it.

Korean nouns usually do not have to show singular or plural.

So 만두 can mean:

• a dumpling
• dumplings
• sometimes even an order of dumplings, depending on context

In English, we often need to choose singular or plural, but Korean often leaves that unstated unless it matters.

It comes from 주문하다, which means to order.

Breakdown:

• 주문하다 = to order
• 주문했어요 = ordered

More specifically:

• 하 changes to 해
• past tense adds -었-
• polite ending is -어요

So:

• 주문하다
• 주문해요 = order / am ordering
• 주문했어요 = ordered

This is a polite, everyday style.

Because Korean often leaves out the subject when it is understood from context.

In English, you usually need to say I:

• I was hungry, so I ordered dumplings

In Korean, if it is obvious who is talking about, you can just say:

• 배가 고파서 식당에서 만두를 주문했어요.

The listener naturally understands that the speaker means I.

Because Korean is generally a subject-object-verb language, unlike English, which is usually subject-verb-object.

English:

• I ordered dumplings

Korean:

• (I) dumplings ordered
• 만두를 주문했어요

Also, the reason clause comes before the main action:

• 배가 고파서 = because I was hungry
• 식당에서 만두를 주문했어요 = I ordered dumplings at a restaurant

So the overall Korean word order is very natural: Because I was hungry, at the restaurant dumplings ordered.

That sounds strange in English, but it is normal in Korean.