syawohago naseo chinguga je meorireul deuraieoro mallyeo jwosseoyo.

-고 나서 means after doing... or once ... is finished.

So:

• 샤워하다 = to shower
• 샤워하고 나서 = after showering

It shows that the shower happened first, and then the next action happened afterward.

Compared with just -고, -고 나서 makes the sequence a little clearer and stronger:

• 샤워하고 친구가 제 머리를 말려 줬어요 = I showered, and then my friend dried my hair.
• 샤워하고 나서 친구가 제 머리를 말려 줬어요 = After showering, my friend dried my hair.

Both can work, but -고 나서 emphasizes completed order more clearly.

Here, 가 marks 친구 as the subject of the action 말려 줬어요.

• 친구가 = my friend is the one who did it
• 친구는 would sound more like setting up my friend as the topic, possibly with contrast

In this sentence, 친구가 feels natural because it identifies who dried the hair.

Compare:

• 친구가 제 머리를 말려 줬어요 = My friend dried my hair for me.
• 친구는 제 머리를 말려 줬어요 = As for my friend, they dried my hair for me.
  This can sound contrastive depending on context.

제 is the shortened form of 저의, and it is the polite/humble way to say my.

So:

• 내 = my, casual
• 저의 = my, polite/humble
• 제 = shortened, very common polite form of 저의

Because the sentence ends politely with -어요, using 제 matches that politeness level well.

So these are related:

• 내 머리 = my hair, casual
• 저의 머리 = my hair, polite but a bit more formal/stiff
• 제 머리 = my hair, polite and natural

머리 can mean either head or hair, depending on context.

In this sentence, because of 드라이어로 말리다 (to dry with a dryer), 머리 is understood as hair.

So:

• 머리를 말리다 = to dry one’s hair
• not literally dry the head itself

Korean often uses 머리 where English specifically says hair.

You could also say 머리카락, which more specifically means hair strands/hair, but 머리 is much more natural in everyday speech here.

Because the thing being dried is the hair, not the person.

In English we also usually say:

• My friend dried my hair rather than
• My friend dried me

Korean works the same way here:

• 제 머리를 말리다 = dry my hair

So 를 is attached to 머리, which is the direct object of the verb.

-로 here marks the tool or means used to do something.

So:

• 드라이어 = dryer / hair dryer
• 드라이어로 = with a dryer / using a dryer

This is a very common use of -로:

• 가위로 잘랐어요 = I cut it with scissors.
• 펜으로 썼어요 = I wrote it with a pen.
• 드라이어로 말렸어요 = I dried it with a dryer.

So in your sentence, 드라이어로 tells you what instrument the friend used.

It is understandable and correct, but in everyday Korean, people also very often say:

• 드라이기
• 헤어드라이어

Depending on the speaker, 드라이기 may sound even more common in casual speech.

So these can all appear:

• 드라이어로 말렸어요
• 드라이기로 말렸어요
• 헤어드라이어로 말렸어요

Your sentence is still perfectly understandable.

This is an important pattern.

• 말리다 = to dry something
• 말려 줬어요 = dried it for me

The 주다 part adds a benefactive meaning: someone did the action as a favor or for the benefit of someone else.

So:

• 친구가 제 머리를 말렸어요 = My friend dried my hair.
• 친구가 제 머리를 말려 줬어요 = My friend dried my hair for me.

That extra 주다 often gives a feeling of kindness, help, or doing a favor.

Yes. It comes from 말리다.

The conjugation works like this:

• dictionary form: 말리다
• polite present: 말려요
• polite past: 말려 줬어요

The 리 + 어 combination becomes 려, so 말리어 becomes 말려.

Then:

• 주었어요 contracts to 줬어요

So:

• 말려 주었어요 → 말려 줬어요

That is a normal contraction in spoken and written Korean.

Yes, there is another 말리다 that means to stop someone, to hold someone back, or to dissuade.

For example:

• 친구를 말렸어요 = I stopped my friend / tried to dissuade my friend.

But in your sentence, because of 머리를 and 드라이어로, the meaning is clearly to dry:

• 머리를 드라이어로 말리다 = to dry hair with a dryer

So context makes the meaning obvious.

줬어요 is past tense polite informal style, often called 해요체.

That means it is polite and very common in everyday conversation.

Related forms:

• 줘요 = gives / does for me, polite present
• 줬어요 = gave / did for me, polite past
• 줬습니다 = more formal past
• 줬어 = casual past

So the sentence sounds polite and natural for normal conversation.

Sometimes yes, because Korean often leaves out things that are obvious from context.

For example, if it is already clear whose hair you mean, someone might say:

• 친구가 머리를 드라이어로 말려 줬어요

and listeners would understand it as my hair from the situation.

However, including 제 makes it clearer, especially for learners or when context is limited.

So:

• 제 머리를 = explicit and clear
• 머리를 = possible if the context already makes it obvious

Korean word order is fairly flexible as long as the particles stay correct.

Your sentence uses a very natural order:

• 샤워하고 나서 = after showering
• 친구가 = my friend
• 제 머리를 = my hair
• 드라이어로 = with a dryer
• 말려 줬어요 = dried for me

You could also hear variations like:

• 샤워하고 나서 친구가 드라이어로 제 머리를 말려 줬어요
• 친구가 샤워하고 나서 제 머리를 드라이어로 말려 줬어요

But the original order is smooth and standard. The verb still stays at the end, which is the key rule.