حقوق الركاب مهمة.

Literally, حقوق الركاب means the rights of the passengers or passengers’ rights.

• حقوق = rights
• الركاب = the passengers / passengers

So the whole phrase is an iḍāfa construction, which is often how Arabic expresses X of Y or the English possessive Y’s X.

The singular is حق, which means right.

So:

• حق = a right
• حقوق = rights

This is a broken plural, which means the plural is formed by changing the internal pattern of the word, not just by adding an ending.

Because حقوق الركاب is an iḍāfa construction.

In an iḍāfa:

• the first noun usually does not take الـ
• the second noun determines whether the whole phrase is definite or indefinite

Here:

• حقوق = first part of the iḍāfa
• الركاب = second part, and it has الـ

That makes the whole phrase definite: the passengers’ rights.

Yes, exactly.

حقوق الركاب is an iḍāfa phrase, meaning:

• rights of the passengers
• or more naturally in English, passengers’ rights

This structure is extremely common in Arabic.

Examples of the same pattern:

• كتاب الطالب = the student’s book
• باب البيت = the door of the house
• حقوق الركاب = passengers’ rights

الركاب means the passengers or passengers, depending on context.

It comes from the root related to riding or boarding. In modern usage, راكب means passenger or rider, and الركاب is a common collective/plural form meaning passengers.

So in this sentence, حقوق الركاب naturally means passengers’ rights.

This is a very common Arabic rule:

A non-human plural is usually treated grammatically as feminine singular when it takes an adjective or predicate adjective.

Since حقوق means rights, and rights are non-human, Arabic treats it this way.

So:

• حقوق = plural, but non-human
• therefore the predicate/adjective is feminine singular
• so we say مهمة

This is why Arabic says:

• الكتب جديدة = the books are new
  not جديدون
• البيوت كبيرة = the houses are big
• حقوق الركاب مهمة = passengers’ rights are important

No.

The correct form here is مهمة.

Why?

• مهمون is a masculine sound plural adjective used for human masculine plural
• مهمات would not work here as the adjective in this sentence

Because حقوق is a non-human plural, Arabic normally uses the feminine singular adjective:

• مهمة

So حقوق الركاب مهمة is the correct MSA form.

Here it means important.

That can be confusing, because مهمة can also be a noun meaning mission or task in other contexts.

In this sentence, though, it is functioning as the predicate of the sentence and means:

• important

So the sentence means:

• Passengers’ rights are important

not

• Passengers’ rights are a mission

Because Arabic often uses a nominal sentence in the present tense with no written verb equivalent to English is/are.

So:

• حقوق الركاب مهمة

literally looks like:

• Passengers’ rights important

But in natural English, we translate it as:

• Passengers’ rights are important

This is completely normal in Arabic.

The sentence is a nominal sentence:

• حقوق الركاب = the subject/topic of the sentence (مبتدأ)
• مهمة = the predicate/comment (خبر)

So the structure is:

• حقوق الركاب = passengers’ rights
• مهمة = important

Together: Passengers’ rights are important.

It would be:

حُقُوقُ الرُّكَّابِ مُهِمَّةٌ

With case endings:

• حُقُوقُ = nominative, because it is the مبتدأ
• الرُّكَّابِ = genitive, because it is the second term of the iḍāfa
• مُهِمَّةٌ = nominative, because it is the خبر

In normal everyday writing, these short vowels are usually omitted, so you normally see:

حقوق الركاب مهمة

It is pronounced ar-rukkāb, not al-rukkāb.

That is because ر is a sun letter. When الـ comes before a sun letter, the l sound assimilates to the next consonant.

So:

• written: الركاب
• pronounced: ar-rukkāb

This is a pronunciation rule only; the spelling does not change.

A good pronunciation is:

ḥuqūq ar-rukkāb muhimmah

Rough breakdown:

• حقوق = ḥu-qūq
• الركاب = ar-ruk-kāb
• مهمة = mu-him-mah

If fully pronounced with case endings, it would sound more like:

ḥuqūqu r-rukkābi muhimmatun

But in pause, everyday reading often sounds closer to:

ḥuqūq ar-rukkāb muhimmah

No.

If you wanted to say The passengers are important, you would need a sentence where the passengers themselves are the subject, such as:

الركاب مهمون
or, in some contexts, another appropriate agreement pattern depending on the exact noun form used.

But حقوق الركاب مهمة clearly means:

• Passengers’ rights are important

because حقوق means rights.

Yes. That is a very natural English translation.

Possible translations include:

• Passengers’ rights are important
• Passenger rights are important
• The rights of passengers are important

All of these match the Arabic well, depending on the style of English you want.