قواعد الزيارة مهمة.

Because Arabic often uses a nominal sentence in the present tense, with no written or spoken verb for is/are.

So:

• قواعد الزيارة مهمة literally looks like:
• rules of the visit important

But it means:

• The visiting rules are important / The rules of the visit are important

In the present tense, Arabic usually leaves out is/are. If you wanted the past tense, then a verb would appear, such as كانت or كان depending on the subject.

This is an iḍāfa structure, often called a construct phrase.

Here:

• قواعد = rules
• الزيارة = the visit / visiting

Together:

• قواعد الزيارة = the rules of the visit or visiting rules

In an iḍāfa:

1. The first noun is the thing being possessed or specified.
2. The second noun tells you whose, of what, or what kind.

So this works like X of Y in English.

Other examples:

• كتاب الطالب = the student’s book
• باب البيت = the door of the house

Because in an iḍāfa, the first noun normally does not take الـ.

So you do not say:

• القواعد الزيارة for this meaning

Instead, you say:

• قواعد الزيارة

The whole phrase becomes definite because the second noun is definite:

• الزيارة = the visit / the visiting

So قواعد الزيارة is understood as a definite phrase:

• the rules of the visit
• the visiting rules

This is a key rule of iḍāfa:

• first noun: no الـ
• second noun: can be definite or indefinite
• the definiteness of the whole phrase depends mainly on the second noun

قواعد is a plural word. Its singular is:

• قاعدة = rule

So:

• قاعدة = one rule
• قواعد = rules

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.

That is very common in Arabic.

This is one of the most important agreement patterns in Arabic.

قواعد is a non-human plural. In Modern Standard Arabic, non-human plurals are usually treated grammatically as feminine singular for agreement.

So even though قواعد means rules in English, the adjective or predicate often appears in the feminine singular form:

• مهمة = important (feminine singular)

That is why the sentence is:

• قواعد الزيارة مهمة

and not usually:

• قواعد الزيارة مهمات

This pattern is very common:

• الكتب جديدة = The books are new
• البيوت كبيرة = The houses are big
• القوانين واضحة = The laws are clear

Even though the nouns are plural, the descriptive word is often feminine singular because they are non-human.

The masculine singular form is:

• مهم

The feminine singular form is:

• مهمة

Since قواعد is a non-human plural and takes feminine singular agreement, Arabic uses:

• مهمة

So:

• كتاب مهم = an important book
• قاعدة مهمة = an important rule
• قواعد مهمة = important rules
  literally using feminine singular agreement because of the non-human plural pattern

The sentence has two main parts:

1. قواعد الزيارة = the topic / subject
2. مهمة = the predicate / description

So the structure is:

• قواعد الزيارة = the visiting rules
• مهمة = important

Together:

• The visiting rules are important

In Arabic grammar terms, this is a nominal sentence:

• مبتدأ: قواعد الزيارة
• خبر: مهمة

If fully vowelled, it would usually be:

• قَواعِدُ الزِّيارةِ مُهِمَّةٌ

Here is why:

• قواعدُ: nominative, because it is the subject of the nominal sentence
• الزيارةِ: genitive, because it is the second part of the iḍāfa
• مهمةٌ: nominative, because it is the predicate

So the full grammatical reading is:

• قَواعِدُ الزِّيارةِ مُهِمَّةٌ

In normal everyday writing, these short vowels are usually omitted.

It is usually pronounced:

• qawāʿid

A rough breakdown:

• qa
• wā
• ʿid

The letter ع in the middle is important. It is a consonant that does not exist in English, so learners often need practice with it.

If fully vowelled in this sentence, it is:

• قَواعِدُ
• qawāʿidu in full grammatical pronunciation

But when pausing in normal speech, the final short vowel is often not pronounced.

Yes, depending on context, قواعد الزيارة can be understood in a slightly broader way, such as:

• visiting rules
• rules for visiting
• the rules of the visit

That is because الزيارة can function like a noun meaning the visit or visiting.

Arabic often allows this kind of compact noun relationship, and English may translate it in more than one natural way depending on the situation.

In normal neutral word order, the sentence is best as:

• قواعد الزيارة مهمة

Putting مهمة first is possible only in more marked or stylistic contexts, but for a learner, the standard and safest form is:

• subject first
• predicate second

So it is best to learn this sentence as:

• قواعد الزيارة مهمة

In this sentence, مهمة is best understood as the predicate:

• The visiting rules are important

If you wanted important visiting rules as one noun phrase, you would usually say:

• قواعد الزيارة المهمة

Here, المهمة is an adjective describing قواعد الزيارة inside the noun phrase:

• the important visiting rules

Notice that when the adjective is inside a definite noun phrase, it also becomes definite:

• المهمة

So compare:

• قواعد الزيارة مهمة = The visiting rules are important
• قواعد الزيارة المهمة = the important visiting rules