من الأفضل أن يوصل الفني الكابل بالمقبس.

Arabic often leaves out the present-tense verb to be.

So من الأفضل by itself can mean it is better or it is preferable.
There is no separate word for is here.

If you wanted a past or future meaning, Arabic would usually add a form of كان or يكون.

من الأفضل is a very common expression meaning it is better, it is best, or it is preferable.

In this sentence, it introduces advice or a recommendation:

• من الأفضل أن... = It is better to... / It would be better if...

You do not need to translate من literally here. The whole phrase works as one idiomatic expression.

أن is used before a present-tense verb to introduce an action clause, often after expressions like:

• من الأفضل أن... = it is better to...
• أريد أن... = I want to...
• يجب أن... = it is necessary to...

So:

• أن يوصل الفني الكابل... = for the technician to connect the cable...

Grammatically, أن also puts the following present-tense verb into the subjunctive. In fully vowelled Arabic, that would be:

• يُوصِلُ → normal indicative
• أن يُوصِلَ → subjunctive after أن

In normal writing, that vowel change is usually not shown.

No.

These are different particles:

• أنْ is followed by a verb
• أنَّ is followed by a noun clause

In your sentence, أن is followed by يوصل, which is a verb, so this is أنْ.

This can confuse learners because in ordinary unvowelled writing, أن and أنّ often look the same. The structure of the sentence tells you which one it is.

Because the meaning here is connect, not arrive.

• يصل usually means he arrives or he reaches
• يوصل usually means he causes something to reach, and in many contexts he connects, delivers, or attaches

So:

• يوصل الكابل بالمقبس = he connects the cable to the socket
• يصل إلى... = he arrives at...

This is a very important distinction.

Because Arabic very often uses verb–subject–object order.

So:

• يوصل الفني الكابل = the technician connects the cable

That is a normal Arabic verbal sentence:

• يوصل = verb
• الفني = subject
• الكابل = object

English usually prefers subject + verb, but Arabic often starts with the verb.

Also, after أنْ, Arabic normally expects a verb right away, so أن يوصل... is the natural structure here.

There are two main clues:

1. Word order
After the verb, the first noun is typically the subject, and the next direct noun is often the object.

So:

• يوصل = connects
• الفني = the technician → subject
• الكابل = the cable → object

2. Case endings
In fully vowelled Arabic, the roles are clearer:

• الفنيُّ = subject, nominative
• الكابلَ = direct object, accusative
• بالمقبسِ = after a preposition, genitive

In everyday writing, these endings are usually omitted, so learners rely mostly on word order and meaning.

Because the verb وصّل commonly takes the preposition بـ when it means connect X to Y.

So Arabic says:

• وصّل الكابلَ بالمقبس = connect the cable to the socket

This is the normal pairing for this meaning.

Using إلى would suggest more of a direction or movement to/toward something, rather than the idea of physically connecting one thing with another.

It is made of three parts:

• بـ = with / by / to, depending on context
• ال = the
• مقبس = socket / outlet

Together:

• بـ + ال + مقبس → بالمقبس

So بالمقبس means to the socket / with the socket, and in this sentence the natural English meaning is to the socket or into the socket, depending on context.

Because the sentence is talking about specific, identifiable things:

• الفني = the technician
• الكابل = the cable
• المقبس = the socket

Arabic uses the definite article الـ very often when the context already makes the item clear. In technical or instructional language, this is especially common.

A fully vowelled reading would be approximately:

مِنَ الأفضلِ أنْ يُوصِلَ الفنّيُّ الكابلَ بالمَقْبَسِ.

This shows the grammar more clearly:

• الأفضلِ after مِنَ
• يُوصِلَ because of أنْ
• الفنّيُّ as the subject
• الكابلَ as the direct object
• بالمَقْبَسِ because it follows the preposition بـ

In ordinary texts, these short vowels are usually omitted, so you normally see:

من الأفضل أن يوصل الفني الكابل بالمقبس.

Yes. Depending on context, natural translations could include:

• It is better for the technician to connect the cable to the socket.
• The technician should preferably connect the cable to the socket.
• It would be better if the technician connected the cable to the socket.

The exact English wording may change, but the Arabic structure and meaning stay the same: it is giving a recommendation.