ojeoneneun kapega hangahaeseo gongbuhagi johayo.

Because the two particles are doing different jobs:

• 에 marks a time expression, meaning at / in
• 는 makes that time expression the topic or contrast

So 오전에는 means something like:

• in the morning
• as for the morning
• at least in the morning (depending on context)

The 는 often gives a slight contrast, as if the speaker is talking about the morning in particular, possibly compared with other times of day.

For example, this sentence can feel like:

• In the morning, cafes are quiet, so they’re good for studying.
• maybe implying but later they may be busier

Here, 카페가 marks 카페 as the subject of the descriptive phrase 한가하다.

So the structure is:

• 오전에는 = in the morning
• 카페가 한가해서 = cafes are quiet / not busy, so...
• 공부하기 좋아요 = it’s good to study

Using 가 here sounds natural because the speaker is stating a condition about cafes: cafes are quiet.

If you used 카페는, it would sound more like you are making cafes the topic, perhaps contrasting them with something else:

• 오전에는 카페는 한가해서... = As for cafes, in the morning they’re quiet...

That is possible in some contexts, but 카페가 is the more neutral choice in this sentence.

한가하다 usually means:

• to be free (as in not busy)
• to be quiet / uncrowded
• to be leisurely

In this sentence, for a place like a cafe, it means:

• not crowded
• not busy
• quiet enough

So 카페가 한가하다 here is not saying the cafe itself is literally free in some abstract sense. It means the cafe is calm, not busy, and therefore a good environment for studying.

-아서/어서 is a common connector meaning:

• so
• because
• and so

Since 한가하다 ends in 하다, it changes like this:

• 한가하다
• remove 다
• add -해서
• → 한가해서

So:

• 카페가 한가해서 공부하기 좋아요
• The cafe is quiet, so it’s good for studying

This pattern is extremely common in Korean:

• 싸서 좋아요 = It’s cheap, so it’s nice
• 조용해서 좋아요 = It’s quiet, so it’s nice
• 가까워서 좋아요 = It’s close, so it’s nice

This is the pattern:

• verb stem + 기 = turning a verb into a noun-like form
• 좋다 = to be good

So:

• 공부하다 = to study
• 공부하기 = studying / to study
• 공부하기 좋아요 = it is good to study / it is good for studying

In natural English, this sentence usually means:

• It’s good for studying
• It’s a nice place to study

So 공부하기 is not the main verb of the sentence. The main predicate is 좋아요.

Not exactly.

• 공부하기 좋아요 = It’s good to study / It’s good for studying
• 공부하는 것을 좋아해요 = I like studying

That is an important difference.

In your sentence, the idea is about the situation or environment being suitable for studying, not about someone personally enjoying studying.

So:

• 오전에는 카페가 한가해서 공부하기 좋아요 = In the morning, cafes are quiet, so they’re good for studying

not

• In the morning, I like studying because cafes are quiet

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

In English, we often need something like:

• it’s good for studying
• they’re quiet
• I like it

But in Korean, those can be omitted if the meaning is clear.

So in this sentence, Korean does not need an explicit it:

• 공부하기 좋아요 literally looks like studying is good
• but naturally means it’s good for studying

The listener understands that the speaker is talking about the cafe environment in the morning.

It can be either, depending on context.

Korean nouns usually do not have to show singular vs. plural the way English does. So 카페가 can mean:

• the cafe
• a cafe
• cafes

In this sentence, the most natural English translation is often plural and general:

• Cafes are quiet in the morning, so they’re good for studying

But if you were talking about one specific cafe, it could also mean:

• The cafe is quiet in the morning, so it’s good for studying

Context decides.

Both can relate to the morning, but they are not exactly the same.

• 오전 = A.M. / the morning hours before noon
• 아침 = morning, often with a more everyday or lifestyle feeling, and it can also mean breakfast in some contexts

So:

• 오전에는 sounds a bit more time-based and objective
• 아침에는 can sound more like in the morning in daily life

In this sentence, 오전에는 fits well because the speaker is talking about a time period when cafes tend to be less busy.

좋아요 is the polite informal style, sometimes called 해요체.

It is:

• polite
• very common in everyday conversation
• appropriate in many normal situations

Related forms:

• 좋아 = casual
• 좋아요 = polite
• 좋습니다 = more formal

So this sentence is polite and natural for daily speech:

• 오전에는 카페가 한가해서 공부하기 좋아요.

No, that would require a different structure.

This sentence says:

• In the morning, the cafe is quiet, so it is good for studying

The final part is 공부하기 좋아요, which describes suitability or convenience for studying.

If you wanted to say I study in the morning because the cafe is quiet, you would say something more like:

• 카페가 한가해서 오전에 공부해요.

So the original sentence is about how good the environment is for studying, not about the speaker’s action itself.