הנימוק שלה היה ברור מספיק כדי שאבין למה היא סירבה.

Not exactly.

נימוק usually means reasoning, justification, or argument—the explanation someone gives to support what they did or said.

סיבה is more general and often means simply reason or cause.

So in this sentence, הנימוק שלה is not just her reason in a broad sense, but more specifically the explanation/justification she gave.

Because the phrase is definite: it means her reasoning, meaning a specific reasoning.

In Hebrew, when a noun is followed by של + pronoun to show possession, the noun is often made definite with ה:

• הנימוק שלה = her reasoning
• הספר שלי = my book

Without ה, נימוק שלה would sound less standard in most contexts, or it could suggest something like a reason of hers, which is not what this sentence wants.

שלה means hers / of her.

It comes from של + a pronoun ending.

Some common forms:

• שלי = mine / my
• שלך = yours
• שלו = his
• שלה = hers / her

After a noun, it works like possession:

• הנימוק שלה = her reasoning
• literally: the reasoning of her

This is a very common Hebrew way to express possession.

Because היה and ברור agree with הנימוק, not with שלה and not with היא later in the sentence.

• נימוק is masculine singular
• so Hebrew uses:
  • היה = masculine singular was
  • ברור = masculine singular clear

So:

• הנימוק שלה היה ברור

Later, the sentence switches to a different subject:

• היא סירבה

There the subject is היא, so the verb is feminine singular: סירבה.

Yes. Both ברור מספיק and מספיק ברור can mean clear enough.

In this sentence:

• ברור מספיק = clear enough

Hebrew allows מספיק either before or after the adjective in many cases.

So both are possible:

• הנימוק שלה היה ברור מספיק
• הנימוק שלה היה מספיק ברור

The difference is mostly one of style or emphasis, not basic meaning.

כדי ש introduces a clause meaning something like so that or in order that.

Here, because it follows מספיק, the whole structure means:

• clear enough for me to understand
• or clear enough so that I understood / could understand

So this part:

• כדי שאבין

means roughly:

• so that I would understand
• for me to understand

In this sentence, it expresses the result of the reasoning being clear enough.

Because the subject of the second action is different.

A very useful rule:

• כדי + infinitive is common when the subject stays the same
• כדי ש + conjugated verb is used when there is a different subject

Here:

• main clause subject: הנימוק שלה
• subordinate clause subject: I (understood from אבין)

So Hebrew uses:

• כדי שאבין

not:

• כדי להבין

Also, שאבין is just ש + אבין written together.

This is a very common Hebrew pattern.

After כדי ש, Hebrew normally uses the form that looks like the future:

• שאבין

But here it does not mean simple future time like I will understand later.

Instead, it expresses something like:

• so that I would understand
• so I could understand
• for me to understand

Because the main clause is past:

• היה ברור מספיק

the whole sentence is understood in a past context. So אבין here is best understood functionally, not as a literal future.

Yes, מדוע could also be used.

• למה = why
• מדוע = why, but more formal

So:

• למה היא סירבה
• מדוע היא סירבה

both mean why she refused

In everyday Hebrew, למה is very common and natural.

It is an embedded question, not a direct question.

The whole sentence is a statement:

• Her reasoning was clear enough for me to understand why she refused.

Inside that statement, למה היא סירבה means why she refused.

Because it is not being asked directly, the full sentence does not need to be written as a question.

This is similar to English:

• I know why she left.

That is not a question either, even though why she left contains question meaning.

סירבה is the past tense, feminine singular form of לסרב, meaning to refuse.

So:

• היא סירבה = she refused

Compare:

• הוא סירב = he refused
• היא סירבה = she refused
• הם סירבו = they refused

The verb matches היא, which is feminine singular.

It is closer to result here.

The idea is not really that the reasoning had an intention. Rather, it was clear enough, and as a result, the speaker could understand why she refused.

So the sentence means something like:

• Her reasoning was sufficiently clear for me to understand why she refused.

Even though כדי ש often introduces purpose, in sentences with מספיק it can naturally express this kind of enough to / enough for someone to meaning.

Yes, it is natural and correct.

A learner might also encounter a very similar word order:

• הנימוק שלה היה מספיק ברור כדי שאבין למה היא סירבה

This means the same thing.

So the sentence you have is good Hebrew, and the main things to notice are:

• הנימוק שלה = her reasoning
• היה ברור מספיק = was clear enough
• כדי שאבין = for me to understand / so that I would understand
• למה היא סירבה = why she refused