oneul doseogwaneseo chingureul dasi mannaseo jeongmal bangawosseoyo.

오늘 means today, and time expressions in Korean often come near the beginning of the sentence.

So:

• 오늘 = today
• 도서관에서 = at the library
• 친구를 다시 만나서 = meeting my friend again
• 정말 반가웠어요 = I was really glad / it was really nice

This is a very natural Korean order: time + place + object + verb-related parts.

English usually has a more fixed word order, but Korean is more flexible. Putting 오늘 first helps set the scene right away.

도서관 means library, and 에서 marks the place where an action happens.

So:

• 도서관 = library
• 도서관에서 = at the library / in the library

In this sentence, the action is meeting someone, and that action happened at the library, so 에서 is the correct particle.

Compare:

• 도서관에서 공부했어요. = I studied at the library.
• 도서관에서 친구를 만났어요. = I met a friend at the library.

친구를 uses the object marker 를 because 친구 is the person being met.

The verb 만나다 means to meet, and in Korean it normally takes a direct object:

• 친구를 만나다 = to meet a friend

So here:

• 친구를 = friend + object marker
• 친구를 다시 만나서 = because I met my friend again / meeting my friend again

Why not the others?

• 친구가 would mark friend as the subject
• 친구는 would mark friend as the topic

But in this sentence, friend is the object of meet, so 를 is natural.

This is just how the Korean verb works.

In English, meet can feel a bit like a two-person action, but grammatically we still say meet a friend, not usually meet with a friend in casual conversation. Korean works similarly:

• 친구를 만나다 = to meet a friend

So Korean treats the person you meet as the direct object.

You may also see 친구를 만났어요 very often in everyday Korean.

다시 means again.

So:

• 친구를 다시 만나서 = meeting my friend again / because I met my friend again

It tells us that the speaker had met this friend before, and then saw them again today.

A simple contrast:

• 친구를 만났어요. = I met my friend.
• 친구를 다시 만났어요. = I met my friend again.

만나서 is the -아서/어서 connective form of the verb 만나다.

It links one idea to the next. In this sentence, it means something like:

• after meeting
• because I met
• having met

So the sentence flows like this:

• 오늘 도서관에서 친구를 다시 만나서 정말 반가웠어요.
• Today, I met my friend again at the library, so I was really glad.

Here, 만나서 connects the event meeting my friend again to the feeling 반가웠어요.

This structure is extremely common in Korean.

반갑다 means to be glad, to be pleased, or to be nice to see someone.

So 반가웠어요 is the past polite form:

• 반갑다 = to be glad / to be pleased
• 반가웠어요 = was glad / was pleased / it was nice

In this sentence, a natural English translation is:

• It was really nice to see my friend again today at the library.

Even though Korean literally says something closer to I was really glad, in context it often means it was nice to see you/them.

Because the speaker is talking about how they felt at that time.

• 반가워요 = I’m glad / it’s nice
• 반가웠어요 = I was glad / it was nice

Since the sentence describes a completed event from earlier today, the past tense sounds natural.

It gives the feeling of reflecting on the experience:

• I saw my friend again, and it was really nice.

The difference is tense.

• 반가워요 = present tense polite
  
  • I’m glad
  • Nice to see you
• 반가웠어요 = past tense polite
  
  • I was glad
  • It was nice to see you

For example:

• 다시 만나서 반가워요. = Nice to see you again.
• 오늘 다시 만나서 반가웠어요. = It was nice to see you again today.

The second one sounds like you are looking back on the meeting after it happened.

정말 means really.

So:

• 반가웠어요 = I was glad / it was nice
• 정말 반가웠어요 = I was really glad / it was really nice

It adds emphasis and makes the feeling stronger.

Similar words include:

• 정말 = really
• 아주 = very
• 너무 = very / so

In this sentence, 정말 sounds natural and sincere.

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

From context, the speaker is the one who felt glad. So the understood meaning is something like:

• I was really glad to meet my friend again today at the library.

Korean often leaves out subjects like I, you, or we when they are obvious from context.

A fuller version could be:

• 저는 오늘 도서관에서 친구를 다시 만나서 정말 반가웠어요.

But in normal conversation, 저는 is often unnecessary.

Yes. The -아서/어서 form can connect ideas in a few related ways, and the exact meaning depends on context.

Here, 만나서 can feel like:

• because I met my friend again
• after meeting my friend again
• having met my friend again

In natural English, we usually do not translate it mechanically. Instead, we say something smooth like:

• It was really nice to see my friend again today at the library.

So the Korean connection is there grammatically, but the best English translation is often more natural and less literal.

Sometimes, but they are not always exactly the same.

• 다시 often means again, with the sense of repeating something
• 또 can mean again, also, or in addition

In this sentence, 다시 만나서 is very natural for meeting again.

• 친구를 다시 만났어요. = I met my friend again.

Using 또 might be possible in some contexts, but 다시 is clearer and more standard here for the idea of seeing someone again.

반가웠어요 is polite, everyday speech.

It is based on the -아요/어요 style, which is common in conversation when speaking politely but not formally.

Levels you might compare:

• 반가워. = casual
• 반가워요. = polite
• 반가웠어요. = polite past
• 반가웠습니다. = more formal past

So 정말 반가웠어요 sounds warm, natural, and appropriate in many everyday situations.

Yes, Korean word order is somewhat flexible, as long as the particles make the roles clear.

The original sentence:

• 오늘 도서관에서 친구를 다시 만나서 정말 반가웠어요.

A variation could be:

• 오늘 친구를 도서관에서 다시 만나서 정말 반가웠어요.

Both are understandable. However, the original sounds very natural because it presents the information in a smooth order:

1. 오늘 = when
2. 도서관에서 = where
3. 친구를 다시 만나서 = what happened
4. 정말 반가웠어요 = how the speaker felt

So yes, Korean allows some movement, but not every order sounds equally natural.

Most naturally, this sentence sounds like the speaker is talking about the experience, not directly saying Nice to see you again to the friend in that exact moment.

It feels like:

• Today I met my friend again at the library, and it was really nice.

If you were speaking directly to the friend, Korean more often uses:

• 다시 만나서 반가워요. = Nice to see you again.
• 오늘 다시 만나서 정말 반가웠어요. = It was really nice seeing you again today.

So the given sentence could work in conversation, but because it includes 친구를, it often sounds like the speaker is talking to someone else about meeting that friend.