yaksok siganeul jakku bakkumyeon chinguga hwanayo.

약속 시간 means the time of an appointment / meeting time / agreed time.

• 약속 = a promise, appointment, arrangement
• 시간 = time

Together, 약속 시간 refers to the time you promised to meet someone.

In this sentence, it means the planned meeting time that keeps getting changed.

Because 시간 is the thing being changed, so it is the object of the verb 바꾸다 (to change).

• 시간을 바꾸다 = to change the time

Here:

• 을/를 marks the object
• 이/가 would mark the subject

So 약속 시간을 자꾸 바꾸면 literally means if you keep changing the appointment time.

자꾸 means repeatedly, again and again, or keep doing something, often with the nuance that it is annoying, unintended, or undesirable.

So in this sentence, 자꾸 바꾸면 suggests:

• you change it over and over
• probably more often than you should
• this repeated action causes a negative reaction

Compare:

• 자꾸 바꾸면 = if you keep changing it again and again
• 계속 바꾸면 = if you continuously keep changing it

자꾸 often sounds more natural here because repeated schedule changes are something people usually find bothersome.

바꾸면 is the verb 바꾸다 (to change) plus the conditional ending -면 (if / when).

So:

• 바꾸다 = to change
• 바꾸면 = if one changes / when one changes

In the sentence:

• 약속 시간을 자꾸 바꾸면 = if you keep changing the meeting time

This -면 clause sets up a condition, and the second part gives the result:

• 친구가 화나요 = your friend gets angry / is upset

It can be understood as either, depending on context.

In this sentence, -면 is often best understood as a general truth or repeated-result pattern:

• If you keep changing the appointment time, your friend gets upset.

It can also feel like:

• When you keep changing the appointment time, your friend gets upset.

English usually chooses if for this kind of advice/warning sentence, but Korean -면 covers both ideas naturally.

친구가 marks friend as the subject of the result clause.

The sentence structure is:

• 약속 시간을 자꾸 바꾸면 = if you keep changing the meeting time
• 친구가 화나요 = the friend gets angry

Using 가 is very natural because it simply marks who experiences the emotion.

If you said 친구는 화나요, it could sound more contrastive, like:

• As for your friend, they get upset
• maybe implying someone else reacts differently

So 친구가 화나요 is the more neutral and natural choice here.

The subject of 바꾸면 is understood from context and is often omitted in Korean.

So the sentence naturally implies:

• If you keep changing the appointment time, your friend gets upset.

Korean often leaves out subjects like you, I, or we when they are obvious. In English, you usually have to include them, but in Korean you often do not.

It can mean either is angry or gets angry / becomes upset, depending on context.

In this sentence, gets upset / gets angry is usually the best translation because it describes the result of the repeated action:

• If you keep changing the meeting time, your friend gets upset.

A useful note:

• 화가 나다 literally means anger comes out / anger arises
• so it often means to become angry

Here 화나요 is the polite present form of that expression.

Both are related to anger, but they are a little different.

• 화가 나다 / 화나요 = to become angry, to be upset
• 화를 내다 = to express anger, to show anger, to get mad outwardly

So:

• 친구가 화나요 focuses on your friend’s emotional state
• 친구가 화를 내요 would focus more on your friend actively showing or expressing anger

In this sentence, 화나요 sounds natural because it describes how your friend feels when you keep changing the time.

It is in the polite informal style, often called 해요체.

• 화나요 ends in -요, which makes it polite
• it is appropriate for everyday conversation, explanations, and most normal situations

Compare:

• 친구가 화나요 = polite
• 친구가 화나 = casual/plain spoken style
• 친구가 화납니다 = more formal

Yes, grammatically you could, but it sounds more formal and less natural in everyday speech.

• 바꾸다 = everyday word for change
• 변경하다 = more formal, more like modify / alter / make a change

For normal conversation about meeting plans, 바꾸다 is much more natural.

So:

• 약속 시간을 자꾸 바꾸면 친구가 화나요 = natural everyday Korean
• 약속 시간을 자꾸 변경하면 친구가 화나요 = understandable, but stiffer and less conversational

It can work either way depending on context.

• 친구가 화나요 literally just says a friend gets upset / the friend gets upset
• Korean often does not specify my, your, the, or a unless needed

In natural English translation, this is often rendered as:

• your friend gets upset
• friends get upset
• a friend gets upset

If this sentence appears in a textbook, it often means something like a general truth:

• If you keep changing the meeting time, your friend will get upset.

The basic Korean structure is:

약속 시간을 / 자꾸 / 바꾸면 / 친구가 / 화나요

You can think of it as:

• 약속 시간을 = the appointment time
• 자꾸 = repeatedly
• 바꾸면 = if you change
• 친구가 = the friend
• 화나요 = gets upset

A natural English order is:

If you keep changing the appointment time, your friend gets upset.

Korean often puts the condition first and the main result at the end. The final verb, 화나요, completes the sentence.