boksunganeun gabange geunyang neoheumyeon an dwaeyo.

는 marks 복숭아 as the topic of the sentence: as for peaches...

So the sentence has a nuance like:

• As for peaches, you shouldn’t just put them in a bag.

Using 는 often gives a general statement, rule, or contrast. It can sound like:

• Peaches, on the other hand, are not something you can just toss into a bag.

If you used 복숭아를, it would sound more like a straightforward object:

• You shouldn’t just put peaches in a bag.

Both are possible, but 복숭아는 feels more like talking about peaches as a category or making a point about them.

It can mean either, depending on context, but here it most naturally means peaches in a general sense.

Korean often does not mark singular vs. plural when it is already clear. So:

• 복숭아 = peach / peaches

If you really wanted to emphasize plural, you might sometimes see 복숭아들, but that is usually unnecessary and can sound unnatural in many contexts.

So in this sentence, 복숭아는 is best understood as peaches or as for peaches.

Here, 에 marks the destination/place something is put into.

With verbs like 넣다 (to put in, insert), the container or destination is often marked with 에:

• 가방에 넣다 = put into a bag
• 상자에 넣다 = put into a box
• 주머니에 넣다 = put into a pocket

So 가방에 means in/into the bag.

A very literal breakdown is:

• 가방에 = into the bag
• 넣으면 = if you put it/them in
• 안 돼요 = it’s not okay / you mustn’t

그냥 usually means just, simply, or without doing anything special.

In this sentence, it adds the nuance of:

• not carefully wrapped
• not protected
• just thrown in normally
• without special treatment

So the sentence is not only saying don’t put peaches in a bag, but more specifically:

• You can’t just put peaches straight into a bag.
• You shouldn’t simply toss peaches into a bag as they are.

That makes sense because peaches bruise easily.

넣으면 comes from the verb 넣다 (to put in) plus the conditional ending -으면.

Breakdown:

• 넣다 = to put in
• 넣으면 = if you put in / when you put in

The -으면 / -면 ending means if or when.

Examples:

• 먹으면 = if/when you eat
• 가면 = if/when you go
• 넣으면 = if/when you put in

So 가방에 그냥 넣으면 안 돼요 literally means something like:

• If you just put them in a bag, it is not okay.

This is a very common Korean pattern:

• Verb + -(으)면 안 돼요

It literally means:

• If you do X, it becomes not okay
• more naturally: You must not do X / You shouldn’t do X

So:

• 넣으면 안 돼요 = You must not put it in / You shouldn’t put it in

Other examples:

• 여기서 사진 찍으면 안 돼요.
  = You must not take pictures here.

• 만지면 안 돼요.
  = Don’t touch it. / You mustn’t touch it.

This pattern is extremely common for giving rules, warnings, and prohibitions.

Yes. Korean often leaves out words that are understood from context.

In this sentence, the thing being put into the bag is understood to be the peaches. Korean does not need to repeat that object.

So the full idea is something like:

• 복숭아는 가방에 그냥 넣으면 안 돼요.
• As for peaches, you mustn’t just put them in a bag.

Even though English usually needs them, Korean can omit it because 복숭아는 already sets the topic.

Yes, that is grammatical.

The difference is mainly nuance:

• 복숭아는 가방에 그냥 넣으면 안 돼요
  = As for peaches, you can’t just put them in a bag.
  This sounds more like a general statement or contrast.

• 복숭아를 가방에 그냥 넣으면 안 돼요
  = You mustn’t just put peaches in a bag.
  This focuses more directly on peaches as the object of 넣다.

So both are possible, but 복숭아는 is especially natural if the speaker is explaining how peaches should be handled.

They differ mainly in politeness level.

• 안 돼 = casual
• 안 돼요 = polite everyday speech
• 안 됩니다 = more formal, firm, or official

So:

• 복숭아는 가방에 그냥 넣으면 안 돼.
  casual, to a friend or younger person

• 복숭아는 가방에 그냥 넣으면 안 돼요.
  polite and natural in everyday conversation

• 복숭아는 가방에 그냥 넣으면 안 됩니다.
  more formal, like instructions or a rule

The sentence you were given uses 안 돼요, which is polite and common.

No, not exactly.

• 안 돼요 means it is not allowed / it is not okay / you shouldn’t
• 못 넣어요 means cannot put in / am unable to put in

So:

• 가방에 그냥 넣으면 안 돼요
  = You mustn’t just put it in a bag.
  This is a rule, warning, or recommendation.

• 가방에 못 넣어요
  = I can’t put it in the bag.
  This focuses on inability.

In your sentence, 안 돼요 is the right choice because the point is not inability, but that doing so would be a bad idea or unacceptable.

It can be either, depending on context and tone.

By itself, -으면 안 돼요 often means:

• you must not
• you shouldn’t
• don’t do that

In this sentence, because it is about peaches being delicate, it often feels like a warning or practical advice:

• Don’t just put peaches in a bag. They’ll get bruised.

So the force is strong grammatically, but in real life it may sound like sensible guidance rather than a harsh command.

A natural pronunciation is approximately:

• 복숭아는 → bok-sung-a-neun
• 가방에 → ga-bang-e
• 그냥 → geu-nyang
• 넣으면 → neo-eu-myeon
• 안 돼요 → an dwae-yo

Two helpful notes:

• 복숭아 is pronounced with a tense-ish sound in the middle by many speakers, close to bok-ssung-a
• 안 돼요 sounds like an dwae-yo, not an doe-yo

So the whole sentence is roughly:

• bok-ssung-a-neun ga-bang-e geu-nyang neo-eu-myeon an dwae-yo