seongjeogeul olliryeomyeon maeil bokseuphaeya haeyo.

Because 성적 is the direct object of 올리다.

• 성적 = grades, scores, academic performance
• 올리다 = to raise, increase, improve

So 성적을 올리다 literally means to raise grades, which in natural English is to improve your grades.

Korean uses 을/를 to mark the object of a transitive verb, so 성적을 is the normal form here.

성적 usually means grades, test scores, or academic performance.

A helpful point for English speakers: Korean nouns usually do not change form for singular or plural. So 성적 can mean:

• a grade
• grades
• academic results

The exact sense depends on context. In this sentence, it most naturally means grades or school performance.

올리다 literally means to raise, to lift, or to increase.

It is used in many situations:

• 가격을 올리다 = to raise the price
• 손을 올리다 = to raise your hand
• 점수를 올리다 / 성적을 올리다 = to raise your score / improve your grades

So in this sentence, 올리다 is being used in the sense of improving academic results.

-려면 is a grammar pattern meaning something like:

• if you want to...
• if you are going to...
• in order to...

So 올리려면 means if you want to improve (them) or to improve (them), depending on how naturally you want to translate it.

In this sentence, it introduces a condition or goal:

• 성적을 올리려면 = if you want to improve your grades / to improve your grades

It often sets up advice about what is necessary to achieve that goal.

This is a very common question.

• 올리면 = if you improve/raise
• 올리려면 = if you want to improve/if you are trying to improve

So -면 is a general if condition, while -려면 often adds the idea of intention, goal, or purpose.

Compare:

• 성적을 올리면 기분이 좋겠어요.
  If your grades improve, you would feel good.

• 성적을 올리려면 매일 복습해야 해요.
  If you want to improve your grades, you have to review every day.

In your sentence, -려면 fits because the speaker is talking about what is needed to achieve a goal.

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

In English, you usually need something like:

• you
• students
• we

But in Korean, if the listener can easily understand who the sentence is about, the subject is often omitted.

So this sentence could imply:

• you have to review every day
• one must review every day
• students need to review every day

All of those are possible depending on context.

매일 means every day. It is an adverb, so it modifies the action 복습해야 해요.

So it tells you how often the reviewing should happen.

Korean adverbs are fairly flexible in position, but putting 매일 before the verb phrase is very natural:

• 매일 복습해야 해요 = you have to review every day

복습하다 means to review, especially to go over material again after learning it.

This is different from the more general 공부하다, which means to study.

So:

• 공부하다 = study in general
• 복습하다 = review what you already learned

That is why 복습하다 is a good choice in a sentence about improving grades. It suggests repeated, disciplined review rather than just vague studying.

Because 해야 해요 expresses necessity or obligation.

• 복습해요 = review / I review / I am reviewing
• 복습해야 해요 = have to review / must review

The pattern is:

• -아/어야 하다 = have to / must

With 하다 verbs, it becomes:

• 하다 → 해야 하다

So 복습해야 해요 means you have to review.

This makes the sentence stronger than a simple statement. It is saying review is necessary if you want the result.

It comes from the grammar pattern -아/어야 하다.

For 하다, the form changes like this:

• 하다
• 하여야 하다
• contracted to 해야 하다
• polite form: 해야 해요

So 복습해야 해요 is built from:

• 복습하다 = to review
• 복습해야 하다 = to have to review
• 복습해야 해요 = polite spoken form

This is one of the most important Korean grammar patterns for expressing obligation.

해요 is the polite informal speech level, often called the 해요 style.

It is very common in everyday conversation because it is:

• polite
• natural
• not overly formal

You could change the sentence depending on the situation:

• 성적을 올리려면 매일 복습해야 해.
  casual

• 성적을 올리려면 매일 복습해야 해요.
  polite everyday speech

• 성적을 올리려면 매일 복습해야 합니다.
  more formal

So the original sentence is polite and natural for speaking to someone respectfully.

Yes, you can.

Both are possible:

• 복습해야 해요
• 복습을 해야 해요

This happens because many noun + 하다 verbs can appear in two related ways:

• as a single verb-like unit: 복습하다
• with the noun marked separately: 복습을 하다

The version without 을 is very common and smooth in everyday speech.
The version with 을 can sound a bit more explicit or slightly more emphatic depending on context.

So in this sentence, 복습해야 해요 is perfectly natural.

Usually it sounds more like advice about what is necessary than a harsh command.

The structure -려면 ... -아/어야 해요 often means:

• if you want X, you need to do Y

So the feeling is:

• If your goal is better grades, daily review is necessary.

It can sound firm, but it is not the same as directly ordering someone with an imperative.

For example, this is more forceful:

• 매일 복습하세요. = Review every day.

Your sentence is more like a statement of requirement tied to a goal.

Korean often uses the present-style form for general truths, habits, rules, and necessities, even when English might use a future expression.

So 복습해야 해요 does not need a future ending here. It naturally means:

• you have to review
• you need to review
• you will need to review

The exact English wording depends on context, but the Korean sentence is already complete and natural without any extra future marking.