i haksaengdeureun doseogwaneseo gongbuhaeyo.

이 means this or these.

In Korean, 이 is used with something close to the speaker. Since 학생들 is plural, 이 학생들 is understood as these students.

A useful comparison:

• 이 학생 = this student
• 이 학생들 = these students
• 그 학생 = that student
• 저 학생 = that student over there

So in this sentence, 이 is pointing to these students.

들 is a plural marker. It makes 학생 (student) into 학생들 (students).

So:

• 학생 = student / students, depending on context
• 학생들 = students

A very important point: Korean does not always need a plural marker. Even without 들, the sentence could still mean the students study at the library if the context makes it clear.

That means:

• 이 학생은 = this student
• 이 학생들은 = these students

Here, 들 is used to clearly show there is more than one student.

Because 는 is a particle, and particles show the role of a word in the sentence.

Here, 는 is the topic particle. It marks 이 학생들 as the topic of the sentence.

So the breakdown is:

• 학생 = student
• 들 = plural
• 은/는 = topic particle

Since 들 ends in a consonant, Korean uses 은 after it. So the full form is:

• 학생들 + 은 → 학생들은

This often gets mentally understood as: As for these students, ...

Both are possible in Korean, but they give slightly different nuance.

• 는/은 marks the topic
• 이/가 marks the subject more directly

So:

• 이 학생들은 도서관에서 공부해요. = As for these students, they study at the library.
• 이 학생들이 도서관에서 공부해요. = These students are the ones who study at the library. or a more neutral subject-marked statement, depending on context

For learners, a simple rule is:

• 은/는 often introduces or contrasts a topic
• 이/가 often focuses more on who is doing the action

In this sentence, 는 sounds very natural if the speaker is talking about these students as the topic.

Because 에서 is used for the place where an action happens.

Here, the action is 공부해요 (study), so the location of that action uses 에서:

• 도서관에서 공부해요 = study at the library

By contrast, 에 is often used for:

1. destination

   • 도서관에 가요 = go to the library

2. existence/location with verbs like 있다

   • 도서관에 있어요 = am/is at the library

So a useful contrast is:

• 도서관에 가요 = go to the library
• 도서관에서 공부해요 = study at the library

공부해요 comes from the verb 공부하다, which means to study.

This verb is built from:

• 공부 = study
• 하다 = to do

So literally, it is like to do study.

When conjugated politely in the present tense:

• 공부하다 → 공부해요

This happens because 하다 changes to 해요 in the -요 polite style.

Examples:

• 공부하다 = to study
• 공부해요 = study / studies / am studying / are studying

This pattern is very common in Korean:

• 운동하다 → 운동해요 = exercise
• 일하다 → 일해요 = work
• 청소하다 → 청소해요 = clean

Because Korean present tense is often broader than English present tense.

공부해요 can mean different things depending on context:

• study
• studies
• am studying
• are studying
• is studying

Korean does not force you to mark the difference the same way English does.

So this sentence could mean:

• These students study at the library.
• These students are studying at the library.

Context tells you which one sounds best in English.

공부해요 is in the polite -요 style.

This is one of the most common everyday polite forms in Korean. It is appropriate in many normal situations, such as speaking to:

• teachers
• coworkers
• people you do not know well
• someone you want to speak politely to

Compare:

• 공부해요 = polite
• 공부합니다 = more formal
• 공부해 = casual/informal

So this sentence is polite but not extremely formal.

The basic Korean order here is:

topic + place + verb

So:

• 이 학생들은 = these students
• 도서관에서 = at the library
• 공부해요 = study

Korean usually puts the verb at the end of the sentence. That is one of the biggest differences from English.

A rough structure is:

[Topic/Subject] [Time/Place/etc.] [Verb]

So this sentence follows a very common Korean pattern.

Yes. In Korean, many nouns do not have to change form for singular vs. plural.

So 학생 can mean:

• student
• students

depending on context.

Then why use 들?

Because 들 can make the plural explicit. It is often used when the speaker wants to clearly emphasize that there is more than one person.

So both are possible:

• 이 학생은 = this student
• 이 학생들은 = these students
• 학생이 공부해요 = a student / the student studies
• 학생들이 공부해요 = students / the students study

Using 들 is not always required, but here it clearly signals students.

A natural pronunciation is close to:

hak-ssaeng-deu-reun

A few helpful notes:

• 학 sounds like hak
• 생 sounds like saeng
• in 학생, the ㄱ from 학 influences the next sound, so it often sounds more like 학쌩 than a careful letter-by-letter 학생
• 들은 sounds like deu-reun

So 학생들은 is often heard approximately as:

학쌩드른

That is the pronunciation, even though the spelling stays 학생들은.

Yes. If the context already makes it clear which students you mean, Korean can omit 이.

For example:

• 학생들은 도서관에서 공부해요. = The students study at the library / Students study at the library

Adding 이 makes it more specific:

• 이 학생들은 도서관에서 공부해요. = These students study at the library

Korean often leaves out words that are obvious from context, but when they are included, they add clarity or emphasis.