المركز مفتوح في الصباح ومغلق في المساء.

Because this is a nominal sentence in Arabic. In the present tense, Arabic usually does not use a separate verb for is / am / are.

So:

• المركز مفتوح = The center is open
• literally: the center open

The idea of is is understood automatically.

If you wanted the past or future, then Arabic would use a verb, for example:

• كان المركز مفتوحًا = The center was open
• سيكون المركز مفتوحًا = The center will be open

It is a nominal sentence (جملة اسمية).

It has:

• المركز = the subject/topic
• مفتوح = the predicate
• في الصباح = a prepositional phrase giving time
• ومغلق = a second predicate connected by و
• في المساء = another time phrase

So the structure is basically:

• المركز
  • مفتوح في الصباح
    • ومغلق في المساء

In English, we often think of this as:

• The center is open in the morning and closed in the evening.

Because here they are predicates, not descriptive adjectives directly attached to the noun.

Compare:

• المركز المفتوح = the open center
  Here المفتوح describes which center, so it has ال to match المركز.

But in your sentence:

• المركز مفتوح = the center is open
  Here مفتوح is the predicate, so it does not take ال.

The same applies to مغلق.

They function like adjectives here, but more specifically they are commonly analyzed as passive participles used adjectivally.

• مفتوح = opened / open
• مغلق = closed / shut

In everyday translation, it is perfectly natural to think of them simply as adjectives meaning open and closed.

This is very common in Arabic:

• الباب مغلق = The door is closed
• المحل مفتوح = The shop is open

They agree with المركز, which is a masculine singular noun.

In Arabic, predicates like these usually match the noun in gender and number.

So:

• المركز مفتوح = masculine singular
• if the noun were feminine singular, you would usually get مفتوحة / مغلقة

For example:

• المدرسة مفتوحة = The school is open
• المدرسة مغلقة = The school is closed

في literally means in, but in time expressions it often means in, during, or in the time of.

So:

• في الصباح = in the morning
• في المساء = in the evening

This use is very common:

• في الليل = at night / in the night
• في الصيف = in the summer

Because Arabic commonly expresses times of day with a preposition + noun:

• في الصباح
• في المساء
• في الليل

This is one of the normal ways Arabic says in the morning, in the evening, and so on.

Arabic also has other time expressions, such as adverbial forms like صباحًا or مساءً, but the version with في is very standard and clear.

و means and.

Here it connects two predicate parts:

• مفتوح في الصباح
• مغلق في المساء

So the sentence is saying two things about المركز:

1. it is open in the morning
2. it is closed in the evening

Arabic often uses و very freely and naturally to join words, phrases, or whole clauses.

Because once the subject المركز has been stated, Arabic can continue with another predicate linked by و without repeating it.

So:

• المركز مفتوح في الصباح ومغلق في المساء

means:

• The center is open in the morning and closed in the evening

English does the same thing:

• We do not usually say The center is open in the morning and the center is closed in the evening.

Because ص is a sun letter. When ال comes before a sun letter, the ل is not pronounced separately; it assimilates to the next consonant.

So:

• الصباح is pronounced approximately aṣ-ṣabāḥ

You will hear a doubled ṣ sound rather than al-ṣ...

But in المساء, م is a moon letter, so the ل is pronounced:

• المساء ≈ al-masā’

So the two words behave differently:

• الصباح → assimilation
• المساء → no assimilation

In normal everyday Arabic writing, short vowel endings are usually omitted.

A fully vocalized version would be something like:

• المركزُ مفتوحٌ في الصباحِ ومغلقٌ في المساءِ

In that version:

• المركزُ has -u because it is the subject
• مفتوحٌ and مغلقٌ have -un as predicates
• الصباحِ and المساءِ have -i because they come after the preposition في

But most real-world Arabic texts leave these endings unwritten, especially outside textbooks, Qur’anic text, or children’s materials.

Yes, but the original order is the most straightforward and neutral.

The normal version is:

• المركز مفتوح في الصباح ومغلق في المساء

You could move time phrases for emphasis, for example:

• في الصباح المركز مفتوح
• في المساء المركز مغلق

But for learners, the original order is the safest and most natural pattern to copy.

Yes, مركز is treated as a masculine noun.

Many Arabic nouns do not have a special ending that clearly marks gender, so gender often has to be learned with the word. A very common feminine marker is ة, but not all feminine nouns have it, and not all nouns without it are masculine by logic alone.

Here, the agreement in the sentence confirms the noun is masculine:

• المركز مفتوح
• not المركز مفتوحة

Not really. This sentence describes a state, not an action happening at a specific moment.

• مفتوح = open
• مغلق = closed

So it means the center is in those conditions at those times.

If you wanted the idea of opens and closes as actions, you would use verbs, for example:

• يفتح المركز في الصباح ويغلق في المساء
  = The center opens in the morning and closes in the evening

So your sentence is about being open/closed, not the action of opening/closing.

Yes. The word المساء ends with اء, and in careful pronunciation it is approximately al-masā’, with a final glottal stop.

So it is not just al-masaa with a long final vowel. There is a final hamza sound at the end.

Learners often overlook that final sound, but it is part of the word.

It is very natural. It is exactly the kind of simple informational sentence you might see in a schedule, notice, or textbook.

The pattern is extremely useful:

• [place] + مفتوح + [time] + ومغلق + [time]

For example:

• المكتبة مفتوحة صباحًا ومغلقة مساءً
• البنك مفتوح يوم الأحد ومغلق يوم الجمعة

So this sentence is a very good model to learn from.