haha ha watasi no goukaku wo yorokobimasita.

母 is the plain word for my mother when talking about your own mother to someone else.

A common pattern is:

• 母 / 父 = used for your own mother/father when speaking to outsiders
• お母さん / お父さん = used when directly addressing your mother/father, or sometimes when referring to someone else’s mother/father more politely

So in this sentence, 母は... is the natural choice if the speaker is telling someone else about their mother.

は marks the topic of the sentence.

So 母は means something like:

• As for my mother, ...
• My mother, ...

It tells the listener that the sentence is going to say something about mother.

In this sentence:

• 母 = mother
• は = topic marker

So the rest of the sentence explains what is true about her: she was pleased about the speaker’s passing.

Here, の connects 私 and 合格 and shows a relationship between them.

私の合格 means:

• my passing
• my success in passing
• literally, the passing of me

The particle の often works like:

• possession: 私の本 = my book
• association/description: 日本の文化 = Japanese culture
• event related to a person: 私の合格 = my passing

So this is not saying I passed as a full clause. It is turning the idea into a noun phrase: my passing.

Because 合格 is being treated as the thing that 母 was pleased about.

• 合格 here is a noun, meaning passing or success in an exam/admission
• を marks what the feeling is directed toward in this sentence

So:

• 合格を喜ぶ = to be pleased about a passing/success

This may feel a little different from English, because English often says be pleased about or be happy about, while Japanese can use を with 喜ぶ.

Here it is a noun.

合格 means passing, successful admission, or success on an exam/test/application, depending on context.

Examples:

• 大学に合格する = to pass / get accepted into a university
• 合格した = passed
• 合格を喜ぶ = to be pleased about the passing

So in your sentence, 合格 is not functioning as a verb. It is the noun passing/success.

The dictionary form is 喜ぶ.

It means:

• to be delighted
• to be pleased
• to rejoice

喜びました is the polite past form:

• 喜ぶ → dictionary form
• 喜びます → polite non-past
• 喜びました → polite past

So the sentence is saying that the mother was pleased.

Because 喜びました describes a completed reaction in the past.

It implies that the mother became happy or was pleased when she learned about the passing.

If you changed it to 喜びます, it would sound non-past, which could mean:

• she is pleased
• she will be pleased
• or a more general/habitual statement, depending on context

But 喜びました is the normal choice if you are narrating what happened.

Yes, and that version is also very natural.

Compare:

• 母は私の合格を喜びました
• 母は私が合格したことを喜びました

The difference is mainly in style and structure:

私の合格を喜びました

• more compact
• noun-based
• slightly more formal or written in feel

私が合格したことを喜びました

• more explicit
• literally Mother was pleased that I passed
• easier to understand for many learners

Both are correct. The original sentence is just a more condensed way to say it.

Because 私 is not the main topic of this sentence. 母 is.

The sentence is about what the mother felt, not directly about what I did.

So the structure is:

• 母は = as for my mother
• 私の合格を = about my passing
• 喜びました = was pleased

If you said 私は, that would make I the topic instead, which would lead to a different sentence focus.

Yes, but it changes the nuance.

• 母は私の合格を喜びました
  = As for my mother, she was pleased about my passing.
• 母が私の合格を喜びました
  = It was my mother who was pleased about my passing / My mother (specifically) was pleased...

So:

• は = topic, broader or more neutral in context
• が = identifies or emphasizes the subject more directly

In many cases, は is the more natural choice when simply telling a story about your mother.

Yes, it is natural.

It is a concise and standard way to say that the speaker’s mother was pleased about the speaker’s passing or success.

It may sound a little more formal or written than a very casual spoken sentence, but it is absolutely normal Japanese.

In casual speech, people might also say things like:

• 母は私が受かって喜びました。
• 母は私の合格をとても喜びました。

But the original sentence is perfectly good.

The spaces are just for learning purposes.

Normal Japanese writing usually does not put spaces between words, so this would normally be written as:

母は私の合格を喜びました。

Textbooks and beginner materials often add spaces to help learners see the parts more clearly:

• 母
• は
• 私
• の
• 合格
• を
• 喜びました

So the spacing is not part of standard written Japanese.