الزميل يعرف بنفسه.

With the intended reading, it is:

az-zamīlu yuʿarrifu binafsihi

A fully vocalized version would be:

الزميلُ يعرّفُ بنفسِهِ

A few pronunciation notes:

• الزميل is pronounced az-zamīl, not al-zamīl, because ز is a sun letter.
• يعرّف has a doubled r sound because of the hidden shadda.
• بنفسه is bi-nafsihi.

Because normal Arabic writing usually leaves out short vowels and often other diacritics too, so يعرف can represent more than one reading.

Here are the two relevant possibilities:

• يَعرِفُ = yaʿrifu = he knows
• يُعَرِّفُ = yuʿarrifu = he introduces / identifies

In this sentence, the phrase بنفسه strongly points to the second reading: يعرّف بنفسه, which is the normal expression for introducing oneself.

So the written form is the same, but the intended meaning tells you how to read it.

بنفسه has three parts:

• بـ = a preposition, usually with / by / in
• نفس = self
• ـه = his

So literally it is something like with his self or by himself, but in Arabic this kind of structure is often how reflexive meaning is expressed.

In this sentence, بنفسه functions idiomatically as part of the expression يعرّف بنفسه.

Because this verb is used in a fixed pattern here.

The expression is:

عرّف بنفسه
= to introduce oneself

So the بـ is not random; it belongs to the construction.
Arabic often uses verbs together with specific prepositions, and you usually have to learn the combination as a unit.

That means it is best to memorize:

• يعرّف بنفسه rather than trying to build it word-by-word from English.

Because Arabic verbs already contain subject information.

In يعرّف, the verb already tells you that the subject is:

• third person
• masculine
• singular

And the sentence also has an explicit subject noun: الزميل.

So Arabic does not need an extra pronoun like هو here. In fact, adding هو would usually be unnecessary unless you wanted special emphasis.

زميل means colleague, classmate, or fellow student/co-worker, depending on context.

The الـ makes it definite, so:

• زميل = a colleague / a classmate
• الزميل = the colleague / the classmate

So the noun here is definite.

Because ز is one of the sun letters.

When الـ comes before a sun letter, the l sound assimilates to the next consonant. So:

• written: الزميل
• pronounced: az-zamīl

You still write الـ, but you pronounce it with assimilation.

Yes, Arabic allows both patterns.

You can have:

• الزميل يعرّف بنفسه
• يعرّف الزميل بنفسه

Both are possible.

Very broadly:

• subject first is common in modern Arabic and feels a bit more like setting the topic first
• verb first is also very normal, especially in more classical-style word order

So this sentence is not strange at all with the noun first.

The fully vocalized sentence is:

الزميلُ يعرّفُ بنفسِهِ

Here is why:

• الزميلُ ends in -u because it is the subject
• يعرّفُ ends in -u because it is a present-tense indicative verb
• نفسِ ends in -i because it comes after the preposition بـ
• ـه is the attached pronoun his

In everyday unvocalized writing, these endings are usually not written.

It would become:

الزميلة تعرّف بنفسها

Pronunciation: az-zamīlatu tuʿarrifu binafsihā

The main changes are:

• الزميل → الزميلة for a female colleague/classmate
• يعرّف → تعرّف for third-person feminine singular
• بنفسه → بنفسها because the pronoun changes from his to her