oneureun doseogwane sarami jeogeoyo.

Here is the sentence piece by piece:

• 오늘은 = today
  • topic marker 은
• 도서관에 = at/in the library
  • location particle 에
• 사람이 = people / a person
  • subject marker 이
• 적어요 = are few / is few in number

So the structure is basically:

As for today, at the library, people are few.

That sounds unnatural in English, but it matches how Korean organizes the sentence.

은/는 is the topic marker. It sets the background or frame for what follows.

So 오늘은 means something like:

• as for today
• today, ...
• when it comes to today

It can also add a slight contrast, like today in particular.

If you said 오늘이, that would make today the grammatical subject, which is not what this sentence is doing.

This is a very common question.

In this sentence, 도서관 is the place where a situation exists. Korean usually uses 에 for a place of existence or state, especially with expressions like:

• 있다 / 없다 = to exist / not exist
• 많다 / 적다 = to be many / to be few

So:

• 도서관에 사람이 많아요 = There are many people at the library.
• 도서관에 사람이 적어요 = There are few people at the library.

By contrast, 에서 is mainly used for a place where an action happens:

• 도서관에서 공부해요 = I study at the library.

Since 적어요 describes a condition, not an action, 에 is the natural choice.

이/가 marks the grammatical subject, and in sentences like this it often points out what exists or what is numerous/few at a location.

So here:

• 도서관에 사람이 적어요 = At the library, people are few.

Using 사람은 would change the nuance. It might sound more contrastive, like:

• As for people, they are few
  maybe implying something is being compared with something else.

In a simple neutral statement, 사람이 is the normal choice.

Korean nouns usually do not have to show singular vs. plural the way English does.

So 사람 can mean:

• a person
• people

The context tells you which one is meant.

Here, because the sentence is about how crowded the library is, 사람이 적어요 is naturally understood as there are few people.

You could say 사람들이, but that would usually be unnecessary here.

적어요 comes from 적다, which means:

• to be few
• to be small in number

It is not the same as 작다, which means to be small in size.

For example:

• 사람이 적어요 = There are few people.
• 방이 작아요 = The room is small.

So 적어요 is about quantity, not physical size.

Korean often does not need a separate expression like English there are.

English says:

• There are few people at the library today.

Korean can simply say:

• 오늘은 도서관에 사람이 적어요

The idea of there are is handled by the overall sentence structure:

• location
• subject
• descriptive word like 많다 or 적다

So Korean often sounds more like:

• At the library, people are few.

That is normal Korean grammar, even if the English translation uses there are.

In Korean grammar, 적다 is usually treated as a descriptive verb. Many textbooks for beginners call this an adjective, because it describes a state or quality.

So in learner-friendly terms, you can think of it as an adjective-like word meaning few.

Its polite present form is:

• 적어요

Its dictionary form is:

• 적다

Yes, you can.

• 오늘은 도서관에 사람이 적어요
• 오늘 도서관에 사람이 적어요

Both are understandable.

The version with 은 sounds a little more like as for today or today, specifically. It gives 오늘 clearer topic status.

The version without 은 is also natural, just slightly less marked.

적어요 is in the polite -아요/어요 style, often called 해요-style.

It is very common in everyday conversation and neutral polite speech.

Related forms are:

• 적다 = dictionary form
• 적어요 = polite everyday form
• 적습니다 = formal polite form
• 적어 = casual/plain intimate form

So this sentence is polite and natural for normal conversation.

It is pronounced approximately like 저거요.

Why? Because when 적 is followed by a vowel, the final ㄱ moves to the next syllable in pronunciation:

• 적어요 → 저거요

This is a normal sound change in Korean pronunciation.

Good question.

• 사람이 적어요 = There are few people.
• 사람이 없어요 = There are no people / there is nobody.

So 적어요 means not many, while 없어요 means none.

That is an important difference:

• 적다 = few
• 없다 = not exist / none / not have