gugi neomu jjamyeon mureul jogeum deo neoheoyagessda.

Because 국 is the thing being described as salty. In this clause, 짜다 means to be salty, so 국 is the subject of that description.

• 국이 짜다 = The soup is salty
• not 국을 짜다, because that would suggest soup is the object of some action, which is not what is happening here

So 국이 너무 짜면 means if the soup is too salty.

Here, 너무 means too.

That is because the sentence implies a problem and a solution:

• The soup is too salty
• so I should add a little more water

In Korean, 너무 can sometimes mean very in casual speech, but in a sentence like this, where the speaker reacts to an undesirable situation, too is the most natural interpretation.

짜면 is the conditional form of 짜다 (to be salty).

It breaks down like this:

• 짜다 = to be salty
• stem: 짜-
• -면 = if / when

So:

• 짜면 = if it is salty
• 너무 짜면 = if it is too salty

This -면 form is a very common way to make if clauses in Korean.

Korean often leaves out subjects when they are obvious from context.

In 물을 조금 더 넣어야겠다, the understood subject is something like I:

• (내가) 물을 조금 더 넣어야겠다
• I should add a little more water

Because it is clear that the speaker is talking about their own decision, Korean normally omits 내가 here.

It means a little more water.

Breakdown:

• 물 = water
• 물을 = water + object marker 을
• 조금 = a little
• 더 = more

So:

• 물을 넣다 = to add water
• 물을 조금 넣다 = to add a little water
• 물을 조금 더 넣다 = to add a little more water

Here, 더 shows that the speaker wants to increase the amount beyond what it has now.

Because 물 is the object of the verb 넣다 (to put in / add).

In other words, water is the thing being added.

• 물을 넣다 = add water
• 소금을 넣다 = add salt
• 야채를 넣다 = add vegetables

So 을/를 marks the thing directly affected by the action.

It combines several grammar pieces:

• 넣다 = to put in / add
• 넣어야 하다 = have to add / should add
• 넣어야겠다 = I guess I should add / I should probably add

A simple way to understand it is:

• -아/어야 하다 = must / have to / should
• -겠- adds the speaker’s judgment, intention, or realization

So 넣어야겠다 feels like:

• I should add some
• I guess I should add some
• Looks like I need to add some

It sounds natural for a speaker making a decision on the spot.

They are similar, but the nuance is different.

• 넣어야 한다 = one must add / should add
  
  • more plain, objective, or explanatory
• 넣어야 해요 = need to add / should add
  
  • common polite everyday form
• 넣어야겠다 = I should add / I guess I should add
  
  • sounds like the speaker is realizing or deciding this right now

So in this sentence, 넣어야겠다 matches the feeling of noticing a problem and deciding on a solution.

That is the normal Korean pattern.

Korean very often puts background or condition first, and the main result later:

• 국이 너무 짜면 = if the soup is too salty
• 물을 조금 더 넣어야겠다 = I should add a little more water

So the structure is:

condition + result

This is very common in Korean and often feels more natural than putting the main clause first.

It can mean either depending on context, but here soup is the most natural translation.

국 is a Korean word for a soup-like dish, often lighter and more broth-based than some Western soups. In English, learners will usually see it translated simply as soup.

So:

• 국이 너무 짜면 = if the soup is too salty

Yes. In everyday speech, 좀 더 is very common and natural.

• 조금 더 = a little more
• 좀 더 = a little more

The difference is mostly style:

• 조금 더 sounds slightly fuller or a bit more careful
• 좀 더 sounds more conversational

So 물을 좀 더 넣어야겠다 would also be very natural.

A natural pronunciation is close to:

구기 너무 짜면 무를 조끔 더 너어야게따

A few helpful notes:

• 국이 often sounds like 구기
• 조금 is often pronounced closer to 조끔
• 넣어야겠다 is said smoothly, roughly like 너어야게따

You do not need to pronounce every written consonant in a very separate way. Korean sound changes make connected speech smoother.