المركبة سليمة، والمرآة الجانبية والزجاج الأمامي نظيفان.

Because this is a present-tense nominal sentence in Arabic. In Modern Standard Arabic, you normally do not use a verb for is/are in the present.

So:

• المركبة سليمة = The vehicle is intact / safe
• not something like المركبة تكون سليمة in normal neutral MSA

If you wanted was or will be, then you would usually use a verb such as كان or سيكون.

المركبة is a grammatically feminine noun. One common sign of this is the ending ـة.

In Arabic, the predicate adjective agrees with the noun in:

• gender
• number

So:

• مركبة = feminine singular
• سليمة = feminine singular

That is why you get المركبة سليمة rather than المركبة سليم.

Because in Arabic, attributive adjectives normally come after the noun they describe.

So:

• المرآة الجانبية = the side mirror
• الزجاج الأمامي = the front glass / windshield

This is the opposite of normal English word order, where the adjective usually comes first.

Arabic pattern:

• noun + adjective

English pattern:

• adjective + noun

Because an adjective that directly describes a noun must match it in definiteness.

So if the noun is definite with الـ, the adjective must also be definite:

• المرآة الجانبية
• الزجاج الأمامي

This is standard adjective agreement in Arabic. The adjective matches the noun in:

• definiteness
• gender
• number
• case

Because سليمة and نظيفان are not attributive adjectives here; they are predicates.

That is an important distinction:

• المركبة السليمة = the intact vehicle
  
  • here السليمة is an adjective directly attached to the noun
• المركبة سليمة = the vehicle is intact
  
  • here سليمة is the predicate of the sentence

Likewise:

• المرآة الجانبية والزجاج الأمامي نظيفان = the side mirror and the windshield are clean

So the lack of الـ helps show that these words are functioning as predicates, not as part of a noun phrase.

Because it refers to two things together:

• المرآة الجانبية
• الزجاج الأمامي

Arabic has a special grammatical number called the dual, used for exactly two.

So:

• singular: نظيف
• dual: نظيفان
• plural: different forms depending on context

Since the sentence is talking about exactly two items being clean, the predicate is dual: نظيفان.

Because the two nouns are of mixed grammatical gender:

• المرآة is feminine
• الزجاج is masculine

When Arabic has mixed gender agreement, the masculine form is normally used as the default.

So the dual predicate becomes:

• نظيفان = masculine dual

If both nouns were feminine, you would expect:

• نظيفتان

A fully vocalized version would be:

المَرْكَبَةُ سَلِيمَةٌ، وَالمِرْآةُ الجَانِبِيَّةُ وَالزُّجَاجُ الأَمَامِيُّ نَظِيفَانِ.

In careful grammatical analysis, these are nominative forms because they are the subject and predicate parts of nominal clauses.

A learner does not usually need to write all those short vowels in normal Arabic text, but it can help show the grammar.

Literally:

• المرآة الجانبية = the side mirror
• الزجاج الأمامي = the front glass

In car-related Arabic, الزجاج الأمامي is the normal MSA way to refer to the windshield/windscreen.

So even though the literal wording is front glass, the intended meaning is the car’s front window.

المركبة means vehicle, which is a bit broader and more formal than السيارة.

• المركبة = vehicle
• السيارة = car

So if the context is specifically a car, السيارة would also be natural. But المركبة works well in formal, technical, or inspection-style language.

Because the adjectives express different kinds of condition.

• سليم / سليمة means sound, intact, undamaged, safe
• نظيف / نظيفة means clean

So:

• المركبة سليمة suggests the vehicle is in good condition or not damaged
• المرآة الجانبية والزجاج الأمامي نظيفان says those two parts are clean

This is a natural combination in inspection or condition-report language.