هو يتأخر بسبب السيارة.

In MSA, يتأخر already marks a 3rd person masculine singular subject, so the sentence could simply be:

يتأخر بسبب السيارة

That would still mean he is late / he is delayed because of the car.

Adding هو is usually for one of these reasons:

• emphasis: He is the one who is late
• clarity: especially in teaching examples
• contrast: for example, هو يتأخر، لكنها تصل في الوقت = He is late, but she arrives on time

So هو is not required here, but it is perfectly correct.

يتأخر is in the imperfect form.

In Arabic, the imperfect can cover several English ideas depending on context, such as:

• he is late
• he is getting delayed
• he is being delayed
• he comes late / he tends to be late

In this sentence, it most naturally means something like he is late or he is being delayed.

يتأخر comes from the verb تأخر.

It commonly means:

• to be late
• to be delayed
• to fall behind

So in this sentence, it is describing a state or situation: the person is not on time, or his arrival is being delayed.

This verb is very common in everyday Arabic. For example:

• تأخر القطار = The train was delayed
• تأخرتُ عن الدرس = I was late for class

It is pronounced approximately as:

ya-ta-ʾakh-kharu

A few points matter here:

• the تأ contains a hamza sound: ta-ʾa
• the خّ has a shadda, so that consonant is doubled
• the خ is the throaty kh sound, like the ch in German Bach or Scottish loch

So it is not a smooth yataakhar. The middle is more clearly broken and doubled: yata-ʾakhkhar.

بسبب means because of.

It is used before a noun, not a full clause. So here:

• بسبب السيارة = because of the car

Grammatically, بسبب is historically made of:

• بـ = with / by
• سبب = cause / reason

Together they function like because of.

So the structure is:

هو يتأخر + بسبب السيارة
He is late + because of the car

السيارة is definite, meaning the car.

Arabic uses the definite article الـ when the noun is specific or known in the context. So this sentence suggests a particular car is being referred to.

If you said:

بسبب سيارة

that would mean because of a car, which is less specific.

So the difference is:

• بسبب السيارة = because of the car
• بسبب سيارة = because of a car

Because it comes after بسبب, and this expression requires the following noun to be in a genitive relationship.

In fully vowelled MSA, the sentence is:

هُوَ يَتَأَخَّرُ بِسَبَبِ السَّيَّارَةِ

Notice the kasra sound at the end of السَّيَّارَةِ.

You can think of it this way:

• بِـ makes سبب genitive
• سبب is then linked to السيارة
• السيارة becomes the second term in the construction, so it is also genitive

Even if case endings are not written in normal text, they are still there grammatically.

Yes, but the structure changes.

بسبب is best when it is followed by a noun:

• بسبب السيارة = because of the car

لأن is usually followed by a full clause:

• لأنه تأخر = because he was late
• لأن السيارة تعطلت = because the car broke down

So for this exact sentence, بسبب is the more natural choice, because the cause is given as a noun phrase, not a whole sentence.

No, Arabic word order is somewhat flexible.

This sentence begins with the pronoun:

هو يتأخر بسبب السيارة

That is a valid subject-first structure.

But you could also hear or see:

يتأخر بسبب السيارة

or, less commonly for neutral style:

يتأخر هو بسبب السيارة

The most natural choice depends on emphasis and style. In many cases, Arabic prefers leaving out the pronoun unless it is needed.

It is active in form.

That said, in meaning it can sometimes feel close to English is delayed, even though Arabic is not using a passive verb here.

So:

• يتأخر = literally something like he becomes late / he is late / he gets delayed
• English may translate it as he is delayed depending on context

If Arabic wanted a clearer passive idea, a different wording could be used, but يتأخر is very normal for this meaning.

The main dictionary forms are:

• هو = he
• تأخر = to be late / to be delayed
• سبب = cause / reason
• سيارة = car

In the sentence, those appear as:

• هو unchanged
• يتأخر = imperfect form of تأخر
• بسبب = because of
• السيارة = the car

This is a good example of how Arabic often builds meaning through patterns and linked nouns rather than separate helper words.