يرتدي صديقي المئزر.

A natural breakdown is:

• يرتدي = he wears / he is wearing
• صديقي = my friend
• المئزر = the apron

So the sentence is literally structured as:

• wears my-friend the-apron

That sounds odd in English, but it is a normal Arabic word order.

Because this is a very common Arabic verbal sentence pattern:

• verb + subject + object

So:

• يرتدي = verb
• صديقي = subject
• المئزر = object

Modern Standard Arabic often uses this verb-first order, especially in straightforward statements.

Yes. That is also correct.

• يرتدي صديقي المئزر = a normal verbal sentence
• صديقي يرتدي المئزر = a nominal sentence with more focus on my friend

Both can mean the same thing in basic translation. The difference is mostly one of style or emphasis.

Because the verb itself already includes that information.

• يرتدي means he wears / he is wearing

So Arabic does not need a separate subject pronoun here. The verb already tells you that the subject is:

• third person
• masculine
• singular

Then صديقي comes after it to specify who that he is.

يرتدي is a present-tense verb, specifically:

• third person masculine singular
• from the past-tense verb ارتدى
• meaning to wear or to put on

In context, يرتدي can mean:

• he wears
• he is wearing

Arabic present tense often covers both simple present and present progressive, depending on context.

The ـي means my.

So:

• صديق = friend
• صديقي = my friend

Literally, Arabic expresses this as something like friend of mine, but in normal English we just say my friend.

Because words with attached possessive endings like ـي are already definite.

So:

• صديق = a friend
• الصديق = the friend
• صديقي = my friend

You do not say الصديقي for my friend.

It is the subject, so it is in the nominative case.

In a fully vowelled version, the sentence would be:

• يَرْتَدِي صَدِيقِي المِئْزَرَ

A useful detail: the final ـي in صديقي hides the usual case ending, so you do not see a clear nominative vowel there, even though the word is functioning as nominative.

It is the direct object, so it is in the accusative case.

In fully vowelled Arabic, you would write:

• المِئْزَرَ

But in normal unvowelled writing, that final fatḥa is usually not shown, so you simply see:

• المئزر

Because the sentence is talking about the apron, not just an apron.

So:

• المئزر = the apron
• مئزرًا = an apron

If you wanted to say My friend is wearing an apron, you could say:

• يرتدي صديقي مئزرًا

It is pronounced approximately:

• al-miʾ-zar

A few points:

• ال = al-
• the ئ contains a hamza, which is a short glottal stop
• so مئزر is not one smooth syllable in the middle; there is a little break: mi-ʾzar

A fully vowelled form is:

• المِئْزَر

Because Arabic hamza changes its written seat depending on the surrounding vowels.

In مِئْزَر, the hamza comes after a kasra sound, so it is written on yaa’ as ئ.

For a beginner, the main thing to remember is simply:

• ئ still represents a hamza
• the pronunciation includes a small glottal stop

They are very close, but not always identical in style.

• يلبس is a very common everyday verb for to wear
• يرتدي is also common, but often sounds a bit more formal or standard in MSA

So both of these can work:

• يرتدي صديقي المئزر
• يلبس صديقي المئزر

In formal written Arabic, يرتدي is very natural.

You would change both the subject word and the verb form:

• ترتدي صديقتي المئزر

That means:

• My female friend wears/is wearing the apron

Changes:

• صديقي → صديقتي
• يرتدي → ترتدي

It can mean either one.

In MSA, the present tense often covers both:

• habitual meaning: my friend wears the apron
• current action meaning: my friend is wearing the apron

Context tells you which meaning is intended.