الدفاع كان ضعيف.

A common Levantine pronunciation is id-difaaʕ kaan ḍaʕeef.

A few notes:

• الدفاع is often pronounced id-difaaʕ or ed-difaaʕ, depending on the speaker.
• The الـ does not sound like al- here, because د is a sun letter, so the l sound blends into the d.
• كان sounds like kaan.
• ضعيف sounds like ḍaʕeef.

So the whole sentence is roughly: id-difaaʕ kaan ḍaʕeef.

كان is the past form of to be.

In Arabic, especially in Levantine:

• For the present, you usually do not say is.
• For the past, you often use كان for was.

So:

• الدفاع ضعيف = The defense is weak
• الدفاع كان ضعيف = The defense was weak

Yes. الدفاع ضعيف means The defense is weak in the present.

That is one of the big differences from English:

• English needs is
• Arabic usually leaves it out in the present tense

So:

• الدفاع ضعيف = present
• الدفاع كان ضعيف = past

Because الدفاع is the subject, the defense, and it is definite.

ضعيف is the description, weak, and in this kind of sentence Arabic normally leaves the predicate adjective indefinite.

So the pattern is very natural:

• الدفاع = the defense
• ضعيف = weak

If you made ضعيف definite too, it would change the meaning and sound like the weak one, not just weak.

Yes. ضعيف agrees with الدفاع in gender and number.

Here:

• الدفاع is grammatically masculine singular
• so the adjective is ضعيف = masculine singular

If the noun were feminine singular, you would usually use ضعيفة instead.

For example:

• الخطة كانت ضعيفة = The plan was weak

Because الدفاع is masculine singular, so the past-tense form used here is كان.

Compare:

• هو كان ضعيف = He was weak
• هي كانت ضعيفة = She was weak

So if the subject were feminine singular, you would usually say كانت, not كان.

Because this sentence is in normal everyday style, as you would expect in Levantine or in unvowelled Arabic writing.

In full formal Arabic grammar, the predicate after كان would take an accusative ending:

• ضعيفًا

But in Levantine speech:

• case endings are not pronounced
• they are usually not written either

So ضعيف is exactly what you would expect in everyday Arabic.

The written sentence الدفاع كان ضعيف can work well for Levantine, and it is also easy for an Arabic speaker to understand in general.

A few differences:

• In Levantine, this is a very normal way to say it.
• In fully formal MSA, you would more carefully say something like كان الدفاع ضعيفًا or write case endings if fully vocalized.

So the sentence is very natural for colloquial use, especially Levantine-style speech.

Yes, you could.

Both are understandable, but they feel a little different:

• الدفاع كان ضعيف sounds very natural in conversation and puts the defense first as the topic.
• كان الدفاع ضعيف can sound a bit more formal, narrative, or written.

In everyday Levantine, putting the noun first is extremely common.

الدفاع can mean different kinds of defense, depending on context.

For example, it could mean:

• a sports defense: the defensive side of a team
• a military defense
• a legal defense

So you understand the exact meaning from the situation, not from the word alone.

Usually the difficult sounds are ض and ع.

• ض is a heavy, emphatic consonant. It is not exactly the same as an English d.
• ع is a deep throat sound that English does not have.

So ضعيف is not just da-eef. It is closer to ḍaʕeef.

Even if your ع is not perfect yet, people will usually still understand you if your pronunciation is reasonably close.

No. ضعيف is used very broadly.

It can describe:

• a weak team
• a weak defense
• a weak argument
• a weak person
• poor quality or poor performance

So in الدفاع كان ضعيف, it usually means the defense was poor, not strong, or ineffective, not necessarily physically weak.