i gugeun eoje meogeun geosboda deol jjaseo joha.

은/는 marks the topic of the sentence. Here, 이 국은 means as for this soup or this soup, ....

So the speaker is introducing this soup as the thing they are talking about, and then making a comment about it:

• 이 국은 = as for this soup
• 어제 먹은 것보다 덜 짜서 좋아 = I like it because it’s less salty than the one I ate yesterday

If you used 이 국이, it would sound more like the soup is being marked as the grammatical subject in a more specific or contrastive way. 이 국은 feels very natural here because the speaker is comparing and commenting on this soup.

먹은 is the adnominal past form of 먹다.

In Korean, when a verb describes a noun, it changes form:

• 먹다 = to eat
• 먹은 = eaten / that I ate

So:

• 어제 = yesterday
• 먹은 = ate / eaten
• 것 = thing

Together, 어제 먹은 것 means the thing I ate yesterday.

This is very common in Korean:

• 어제 본 영화 = the movie I saw yesterday
• 내가 산 책 = the book I bought
• 친구가 만든 음식 = the food my friend made

것 literally means thing, but in sentences like this it often stands in for something already understood from context.

So 어제 먹은 것보다 means:

• than the thing I ate yesterday
• more naturally in English: than the one I ate yesterday

Because the speaker is already talking about soup, 것 is enough. Korean often avoids repeating nouns when the meaning is obvious.

You could think of it like this:

• 이 국은 어제 먹은 국보다...
  = This soup, compared to the soup I ate yesterday...

But Korean often shortens that to:

• 이 국은 어제 먹은 것보다...
  = This soup, compared to the one I ate yesterday...

보다 means than in comparisons.

So:

• 어제 먹은 것보다 = than the one I ate yesterday

It attaches to the noun or noun phrase being compared against.

Examples:

• 나보다 커요 = taller than me
• 어제보다 더워요 = it’s hotter than yesterday
• 이게 저것보다 비싸요 = this is more expensive than that

In your sentence, the comparison is:

• this soup compared to
• the one I ate yesterday

Yes. 덜 means less.

Here:

• 덜 짜다 = to be less salty

So:

• 어제 먹은 것보다 덜 짜서 = because it is less salty than the one I ate yesterday

A useful comparison:

• 더 짜다 = to be more salty
• 덜 짜다 = to be less salty

More examples:

• 오늘은 어제보다 덜 추워요 = Today is less cold than yesterday
• 이 커피는 덜 달아요 = This coffee is less sweet

So 덜 is a very common word for expressing a lower degree of something.

짜서 is 짜다 + -아서/어서, which often means because or links one clause to the next.

Here it gives the reason:

• 덜 짜서 좋아 = I like it because it’s less salty

So the structure is:

• 덜 짜서 = because it is less salty
• 좋아 = I like it / it’s good

In this sentence, -아서/어서 is best understood as a reason connector.

Compare:

• 맛있어서 자주 먹어요 = I eat it often because it’s delicious
• 비가 와서 못 갔어요 = I couldn’t go because it rained

So 짜서 does not just mean and salty here. It means because it is salty / because it is less salty.

It can feel like either one depending on context, and that is very normal in Korean.

• 좋다 basically means to be good
• But in many situations, especially about preferences, it naturally becomes to like

So in this sentence:

• 덜 짜서 좋아
  can be understood as
  I like it because it’s less salty

A more literal breakdown would be something like:

• It’s good / I like it, because it’s less salty than the one I ate yesterday

Korean often leaves the exact English-style subject unstated, so 좋아 can cover both kinds of meaning depending on what sounds natural in English.

The subject I is omitted, which is very common in Korean.

Korean often leaves out subjects, objects, and other information if they are clear from context. In English, you usually need to say I like it, but in Korean the speaker can simply say 좋아.

So this sentence does not explicitly say I, but the meaning is understood from the situation:

• 이 국은 ... 좋아
  = As for this soup, ... I like it / it’s good

This kind of omission is one of the most common things English speakers notice when learning Korean.

A close breakdown is:

• 이 국은 = as for this soup
• 어제 먹은 것보다 = than the thing I ate yesterday / than the one I ate yesterday
• 덜 짜서 = because it is less salty
• 좋아 = I like it / it’s good

So the Korean order is roughly:

This soup, than the one I ate yesterday, less salty-because, I like.

That sounds unnatural in English, but it is very normal in Korean because Korean puts descriptive and modifying material before what it relates to.

In this sentence, that is the most natural interpretation.

Literally, 것 is just thing, so 어제 먹은 것보다 could be translated very literally as than the thing I ate yesterday. But in context, since the speaker is talking about soup, English naturally becomes:

• than the one I ate yesterday

So yes, the phrase is somewhat general on its own, but context tells you what 것 refers to.

Because Korean often avoids repetition when the meaning is obvious.

English might say:

• This soup is less salty than the soup I ate yesterday, so I like it.

But Korean prefers a more compact version:

• 이 국은 어제 먹은 것보다 덜 짜서 좋아.

Using 것 instead of repeating 국 sounds natural and efficient. This happens all the time in Korean conversation.

They are similar, but not the same.

• 덜 짜서 좋아 = I like it because it’s less salty
• 안 짜서 좋아 = I like it because it’s not salty

So 덜 짜다 is comparative: it still may be salty, just not as salty as something else.

That matters here because the sentence includes 보다, a comparison:

• 어제 먹은 것보다 덜 짜서 좋아
  = I like it because it’s less salty than the one I ate yesterday

If you said 안 짜서 좋아, the comparison feeling would be weaker, and it would suggest the soup is simply not salty.

좋아 is the plain/informal style.
좋아요 is the polite style.

So the sentence as written sounds like casual speech, probably said to a friend, family member, or in a relaxed situation.

Compare:

• 이 국은 어제 먹은 것보다 덜 짜서 좋아.
  casual
• 이 국은 어제 먹은 것보다 덜 짜서 좋아요.
  polite

The grammar is the same; only the speech level changes.

Yes, a little.

Because of 은 in 이 국은, the sentence can carry a mild contrastive feeling:

• As for this soup, it’s less salty than the one I ate yesterday, so I like it.

That does not necessarily mean strong emphasis, but 은/는 often creates a sense of setting one thing against another. Since the sentence already compares this soup to yesterday’s one, that slight contrast fits naturally.