يمكن أن يوصي أمين المكتبة بالكتاب بشرط أن يكون متاحا.

As a whole, يمكن أن + present verb is a very common way to express can / may / it is possible to.

So:

• يمكن = it is possible
• أن يوصي = that he recommend / to recommend

Together, يمكن أن يوصي means something like he can recommend or it is possible for him to recommend.

In smooth English, we usually just say can recommend.

Because Arabic often prefers verb-first word order, especially in formal written language.

So this sentence follows a common Arabic pattern:

• يوصي أمين المكتبة = the librarian recommends

Literally, the order is:

• recommend(s) the librarian ...

But in natural English, we reorder it as:

• the librarian recommends ...

This verb–subject–object style is very normal in Modern Standard Arabic.

Literally, أمين المكتبة means the custodian/trustee of the library.

It is an iḍāfa (construct phrase):

• أمين = keeper, custodian, trustee
• المكتبة = the library

Together, the phrase means the librarian.

A useful thing to notice: in an iḍāfa, the first noun does not take الـ, but the whole phrase can still be definite because the second noun is definite.

So:

• أمين مكتبة = a librarian / librarian of a library
• أمين المكتبة = the librarian

Because the verb أوصى / يوصي commonly uses the preposition بـ when it means to recommend something.

So:

• يوصي بالكتاب = he recommends the book

This is just the normal verb-preposition combination to learn with this verb.

Many Arabic verbs work this way: the meaning in English may look like a direct object, but Arabic uses a preposition.

So it is best to learn it as a chunk:

• يوصي بـ ... = recommend ...

بشرط means on condition, provided, or subject to the condition.

It is made from:

• بـ = with / by / under
• شرط = condition

So بشرط أن is a very common expression meaning:

• provided that
• on condition that

In this sentence:

• بشرط أن يكون متاحا = provided that it is available

Because بشرط is followed by a clause introduced by أن.

So:

• بشرط أن ... = provided that ...

This is a fixed and very common structure in Modern Standard Arabic.

Here the clause is:

• أن يكون متاحا = that it be available / that it is available

So the second أن is not redundant; it is the normal way to introduce the condition clause.

يكون is the present form of كان and is often used to mean be in structures like this.

So:

• أن يكون متاحا = that it be available

Arabic often uses يكون where English simply uses be.

This part is describing a state or condition, not an action:

• not that it opens
• but that it is available

So يكون acts as the linking verb between the hidden subject (it) and the adjective متاحا (available).

The subject of يكون is a hidden pronoun meaning it, and it refers back to الكتاب.

So the meaning is:

• provided that it (the book) is available

Arabic often leaves such pronouns unstated when they are understood from context.

So in grammar terms, يكون has an implied subject:

• هو = it / he

And here that implied هو refers to الكتاب.

Because it is the predicate (خبر) of يكون, and the predicate of كان and its sisters is normally accusative.

So:

• يكون = one of the كان-type verbs
• متاحا = its predicate
• therefore متاحا is in the accusative

If the text were fully vowelled, it would be:

• مُتاحًا

In everyday unvowelled writing, it is often written simply as:

• متاحا

Because it agrees with الكتاب, not with المكتبة.

That is a very common point of confusion.

In the sentence, the thing that is available is the book, not the library:

• الكتاب = masculine singular
• so متاحا is masculine singular

If the sentence were talking about the library being available/open/accessible, the form would be different.

So the agreement is with the noun being described, which here is الكتاب.

It is basically impersonal here.

يمكن literally means something like:

• it is possible

Arabic often uses it without an explicit subject, especially in formal language.

So:

• يمكن أن يوصي أمين المكتبة بالكتاب
  = The librarian can recommend the book = literally, It is possible that the librarian recommend the book

In natural English, we usually simplify that to can.

After أن, the following present-tense verb is normally in the subjunctive.

So grammatically, يوصي here is subjunctive.

However, in normal Arabic spelling without short vowels, some verbs do not show an obvious visible change.

That is what happens here. The grammatical change is real, but the unvowelled spelling may look the same.

If fully vowelled, the form would show the subjunctive more clearly:

• أن يُوصِيَ

But in ordinary writing, you usually just see:

• أن يوصي

If fully vowelled, the sentence would be:

يُمْكِنُ أَنْ يُوصِيَ أَمِينُ الْمَكْتَبَةِ بِالْكِتَابِ بِشَرْطِ أَنْ يَكُونَ مُتَاحًا

A learner might find it helpful to break that down like this:

• يمكنُ — final ـُ
• أن يوصيَ — subjunctive after أن
• أمينُ — nominative, because it is the subject
• المكتبةِ — genitive, because it is the second term of an iḍāfa
• بالكتابِ — genitive after the preposition بـ
• بشرطِ — genitive after the preposition بـ
• أن يكونَ — subjunctive after أن
• متاحًا — accusative, because it is the predicate of يكون

In ordinary Arabic text, these short vowels are usually omitted, which is why the sentence looks much simpler on the page.

Yes. Arabic allows different word orders.

For example, you could also say:

أمين المكتبة يمكن أن يوصي بالكتاب بشرط أن يكون متاحا

This puts أمين المكتبة first, more like English:

• The librarian can recommend the book provided that it is available

Both are grammatical, but the original version with the verb first sounds very natural and formal in Modern Standard Arabic.