balpyo yeonseubeul hyudaeponeuro nogeumhae dugo najunge dasi deureoyo.

발표 연습 is a noun phrase made from two nouns:

• 발표 = presentation, speech
• 연습 = practice

Together, 발표 연습 means presentation practice or practicing a presentation.

This kind of noun+noun combination is very common in Korean. Instead of saying something longer like 발표를 연습하는 것, Korean often uses the more compact 발표 연습.

을 is the object marker. It shows that 발표 연습 is the thing being acted on.

Here, the action is 녹음해 두고: you are recording the presentation practice.

So:

• 발표 연습을 = the presentation practice
• 녹음해 두고 = record it and keep it saved

The particle -으로 often marks the tool, method, or means used to do something.

So 휴대폰으로 means with a cellphone / using a cellphone.

In this sentence, it tells you what you use to make the recording.

• 휴대폰으로 녹음하다 = to record using a cellphone

Yes, but the nuance changes.

• 휴대폰으로 녹음하다 = record using a cellphone
• 휴대폰에 녹음하다 = record onto / on the cellphone

The original sentence focuses on the phone as the tool. If you used -에, it would focus more on the phone as the place/device where the recording is stored.

This is 녹음하다 + -아/어 두다 + -고.

The key part is -아/어 두다, which often means:

• do something in advance
• leave it done
• keep it ready for later use

So 녹음해 두다 is not just record. It means something like:

• record it and keep it saved
• record it in advance for later

That fits the next part of the sentence, where you listen to it later.

Because 녹음하고 would simply mean record and... without the extra nuance of preparation.

Compare:

• 녹음하고 = record and then...
• 녹음해 두고 = record it and keep it ready for later

In this sentence, 해 두고 is natural because the recording is meant to be used afterward.

-고 links one action to another, usually like and, and then, or after doing.

So the sentence structure is basically:

• 녹음해 두고 = record it and leave it saved
• 나중에 다시 들어요 = later, listen to it again

It connects the two actions in sequence.

Because 나중에 makes the timing explicit.

• 해 두다 already suggests preparation for later
• 나중에 clearly says later

So using both together is natural. It emphasizes the idea:

Record it ahead of time, and then listen to it later.

This is because 듣다 is a ㄷ-irregular verb.

When ㄷ is followed by a vowel-starting ending like -어요, the ㄷ changes to ㄹ:

• 듣다
  • -어요 → 들어요

So 들어요 is the correct polite present form of 듣다.

A few similar patterns:

• 걷다 → 걸어요
• 묻다 → 물어요 (for the verb meaning to ask)

It is omitted, which is very normal in Korean.

English usually needs it, but Korean often leaves out objects when they are already understood from context.

Here, after saying 발표 연습을 휴대폰으로 녹음해 두고, it is obvious that what you later listen to is that recording.

So Korean does not need to say something like 그것을.

Yes. 다시 means again in this sentence.

So 다시 들어요 means listen again or listen to it again.

It highlights that after recording your practice, you go back and listen one more time.

Because Korean often omits the subject when it is obvious from context.

This sentence could be understood as:

• general advice
• a study tip
• a description of what one usually does

Depending on context, the hidden subject could be something like:

• 저는 = I
• 여러분은 = you
• 우리는 = we

Korean does this very often, much more than English.

들어요 is in the -어요 style, which is polite but not formal-stiff. It is often called the haeyo-style.

That makes the whole sentence sound like:

• neutral explanation
• friendly advice
• polite instruction

So it is a very common everyday style for teaching, giving tips, or describing habits.