يطلي صديقي المزهرية بالطلاء الزجاجي.

يطلي is the present/imperfect tense verb, meaning he paints / he coats / he applies a coating to.

So in this sentence, it refers to my friend doing the action.

A few useful points:

• The basic dictionary form is often given as طلى / يطلي.
• In context, it can mean:
  • to paint
  • to coat
  • to glaze
• The prefix يـ in يطلي tells you it is third person masculine singular: he.

So يطلي صديقي... means My friend paints/coats...

Because Arabic very often uses verb–subject–object order, especially in formal written Arabic.

So:

• يطلي = paints
• صديقي = my friend
• المزهرية = the vase

This gives:

• يطلي صديقي المزهرية
  My friend paints the vase

This word order is completely normal in MSA.

Arabic can also use a subject-first order in some contexts, but the verb-first pattern is extremely common.

The ـي at the end means my.

So:

• صديق = friend
• صديقي = my friend

This is the first-person singular possessive suffix.

It is attached directly to the noun, instead of using a separate word for my.

Compare:

• كتاب = book
• كتابي = my book

So صديقي literally means friend of mine, but naturally we translate it as my friend.

This is a very common learner question.

Normally, the subject of a verbal sentence is in the nominative case. But with a noun like صديقي, the case ending is not obvious in the usual written form because the noun is attached to ياء المتكلم (the suffix meaning my).

So grammatically, صديقي is still the subject, but the case ending is not clearly visible the way it would be on a regular fully inflected noun.

In other words:

• Functionally: it is nominative
• Visually: the ending is masked by the my suffix

This is normal and very common.

Because it is the thing receiving the action of the verb.

In this sentence:

• يطلي = paints/coats
• صديقي = my friend
• المزهرية = the vase

So the vase is what is being painted.

That makes المزهرية the direct object.

In fully vowelled Arabic, it would typically be:

• المزهريةَ

with fatḥa because direct objects are normally accusative.

In everyday unvowelled writing, you usually just see:

• المزهرية

without the ending written.

بـ is a preposition that often means with, by, or using.

So:

• بـ = with / using
• الطلاء = the paint / the coating
• الزجاجي = glass / glass-related

Together:

• بالطلاء الزجاجي = with the glass paint, with the glass coating, or with a glass glaze, depending on context

The بـ shows the material or instrument used to do the painting/coating.

So the structure is:

• يطلي ... بـ...
• he paints/coats ... with ...

Because الزجاجي is an adjective describing الطلاء, and in Arabic adjectives must agree with the nouns they describe in definiteness.

Here:

• الطلاء = the coating/paint
• so the adjective must also be definite:
• الزجاجي = the glass / glass-type

That is why you get:

• الطلاء الزجاجي

not

• الطلاء زجاجي

Arabic adjective agreement includes:

• definiteness
• gender
• number
• case

Since الطلاء is definite, الزجاجي must also be definite.

It describes الطلاء, not المزهرية.

So the phrase is grouped like this:

• بالطلاء الزجاجي
• with the glass coating/paint

The adjective الزجاجي matches الطلاء:

• both are masculine singular
• both are definite

It does not match المزهرية, because المزهرية is feminine.

If it were describing المزهرية, you would expect a feminine adjective, such as something like الزجاجية.

So this sentence means the paint/coating is glass-type, not that the vase is being described here by that adjective.

This is about gender agreement.

• زجاجي = masculine singular adjective
• زجاجية = feminine singular adjective

In the sentence, the adjective modifies الطلاء, which is masculine, so the correct form is:

• الطلاء الزجاجي

If you were describing المزهرية instead, you would use the feminine form:

• المزهرية الزجاجية = the glass vase

So compare:

• الطلاء الزجاجي = the glass coating/paint
• المزهرية الزجاجية = the glass vase

That distinction is very important.

Because the preposition بـ attaches directly to the following word in Arabic spelling.

So:

• بـ
  • الطلاء becomes
• بالطلاء

This is completely normal.

The same thing happens with other short prepositions and particles, for example:

• بِالبيت = in/with the house
• لِلطالب = for the student
• كَالذهب = like gold

So although it is written as one word, you should mentally recognize:

• بـ = preposition
• الطلاء = the noun

Not necessarily literally made of glass.

The adjective زجاجي often means glass, glassy, or glass-related, depending on context. So الطلاء الزجاجي could mean something like:

• glass paint
• glass coating
• glass glaze
• coating for glass
• glass-like coating

The exact English wording depends on the situation.

This is common with nisba adjectives in Arabic: they often express a relationship, not strict material composition.

For example, an adjective like this can mean:

• related to
• intended for
• characteristic of
• associated with

So it is better to think of زجاجي as glass-related unless the context makes the meaning more specific.

Arabic word order is flexible, although some orders are more natural than others.

The original sentence:

• يطلي صديقي المزهرية بالطلاء الزجاجي

is perfectly normal.

But Arabic can sometimes rearrange parts for emphasis, for example:

• صديقي يطلي المزهرية بالطلاء الزجاجي
  • My friend paints the vase with the glass coating

This version puts more focus on my friend.

You can also move prepositional phrases around in some contexts. But for a learner, the original order is a very standard and safe pattern:

• verb + subject + object + prepositional phrase

A careful full reading would be approximately:

yaṭlī ṣadīqī al-mizhariyyata bi-ṭ-ṭilāʾi az-zujājiyyi

A few notes:

• المزهرية is accusative as the direct object, so it would end in -a:
  • المزهريةَ
• الطلاء comes after the preposition بـ, so it is genitive:
  • بالطلاءِ
• الزجاجي is an adjective describing الطلاء, so it also takes the genitive:
  • الزجاجيِّ

In normal unvowelled writing, these endings are usually not shown, but they are still understood grammatically.