من المتوقع أن يعزل الفني الحائط.

من المتوقع is a very common expression meaning it is expected.

Literally, it is something like among the expected things or of what is expected, but in natural English you should understand it simply as:

• It is expected that...
• It is likely that...

So the structure of the sentence is:

• من المتوقع = it is expected
• أن يعزل الفني الحائط = that the technician will insulate/isolate the wall

Yes, this can feel strange to an English speaker.

Here, من is part of the fixed expression من المتوقع. You usually should learn it as one chunk, rather than trying to translate each word separately every time.

So:

• متوقع = expected
• من المتوقع = it is expected / expectedly / likely

Arabic often uses prepositions in idiomatic ways that do not match English exactly.

أن here means that and introduces a verb clause.

So:

• من المتوقع أن... = it is expected that...

It also has a grammar effect: it makes the following imperfect verb subjunctive.

That is why the verb is:

• يعزلَ rather than يعزلُ

In normal unvowelled writing, you usually will not see this difference, but grammatically it is there.

Arabic often uses the imperfect verb after أن to express a future meaning when the context already makes that clear.

So:

• من المتوقع أن يعزل... = it is expected that he will insulate...

You could sometimes also see a future marker in other sentences, but here it is not necessary. The idea of a future event already comes from it is expected that...

يعزل is an imperfect verb form.

The Arabic imperfect can express several ideas depending on context, such as:

• present
• future
• habitual action

In this sentence, because it follows من المتوقع أن, it is understood as future:

• that the technician will insulate/isolate the wall

In Arabic, both of these word orders are possible:

• يعزل الفني الحائط
• الفني يعزل الحائط

The first one is verb–subject–object, which is very common in Modern Standard Arabic.

So in your sentence:

• يعزل = verb
• الفني = subject
• الحائط = object

English usually prefers subject first, but Arabic often does not.

We know from grammar and meaning.

If the sentence is fully vowelled, it would be:

• الفنيُّ = subject, nominative
• الحائطَ = object, accusative

In ordinary Arabic writing, those short vowels are usually not written, so learners must rely on:

1. word order
2. sentence meaning
3. grammar patterns

Since يعزل is something the technician does to the wall, الفني is the doer and الحائط is what receives the action.

Here الفني means the technician.

The word فنّي can be related to technical or specialized work, and as a noun it often means:

• technician
• technical specialist

Depending on context, related forms can have other meanings, but in this sentence the technician is the natural reading.

Not always. The verb عزل can have several meanings depending on context, including:

• to isolate
• to separate
• to remove from office
• to insulate

With الحائط (the wall), the meaning is naturally something like:

• insulate the wall
• possibly isolate/seal off the wall, depending on context

So the object often helps determine the best translation.

الحائط has الـ, so it means the wall.

Arabic uses definiteness a lot, and it may refer to:

• a specific wall already known from context
• a wall understood in the situation
• sometimes a generic item, depending on context

If Arabic wanted to say a wall, it would usually use an indefinite noun:

• حائطًا = a wall

But your sentence specifically has the wall.

Yes. After أنْ, the imperfect verb is normally in the subjunctive.

For this verb, that means the ending is:

• يعزلُ in the indicative
• يعزلَ after أن

This is an important pattern in MSA:

• أريد أن أذهبَ = I want to go
• من المتوقع أن يعزلَ... = it is expected that he will insulate...

In unvowelled text, both are usually written the same way, so learners need to know the rule even when they cannot see the final vowel.

A careful MSA pronunciation would be:

mina l-mutawaqqaʿi ʾan yaʿzila l-fanniyyu l-ḥāʾiṭa

With the grammar endings shown more clearly:

• مِنَ المُتَوَقَّعِ
• أَنْ يَعْزِلَ
• الفَنِّيُّ
• الحَائِطَ

In slower, careful reading:

• الفنيُّ ends with -u because it is the subject
• الحائطَ ends with -a because it is the object

In normal speech or less formal reading, these final case vowels are often reduced or not fully pronounced.

In standard grammar, no—that would not be the normal structure here.

After من المتوقع, the standard pattern is:

• من المتوقع أن + verb

So the correct sentence is:

• من المتوقع أن يعزل الفني الحائط

If you want أنّ followed by a noun, that is a different structure. Here Arabic wants أنْ with a verb clause, not أنّ with a noun clause.