يمزح الولد مع صديقي.

A careful MSA pronunciation is:

yamzaḥu al-waladu maʿa ṣadīqī

Fully vocalized, it is:

يَمْزَحُ الْوَلَدُ مَعَ صَدِيقِي

A few sound notes:

• ḥ represents ح, a stronger, breathier h sound
• ʿ represents ع, a consonant English does not have
• ṣ represents ص, an emphatic s

Also, normal Arabic writing usually leaves out the short vowels, so you often see يمزح الولد مع صديقي without the extra marks.

Because Arabic very often uses verb-first word order in verbal sentences.

So:

يمزح الولد مع صديقي

is a normal MSA pattern: verb + subject + other elements.

English usually prefers subject + verb, but Arabic often begins with the verb. This is one of the most common differences English speakers notice.

You can also say:

الولد يمزح مع صديقي

That is also correct, but it feels more like The boy, he is joking with my friend or puts more focus on the boy.

يمزح is an imperfect verb, here in the 3rd person masculine singular.

That means it can correspond to English meanings like:

• he jokes
• he is joking

In many contexts, the Arabic imperfect can cover both simple present and present progressive, depending on the situation.

So Arabic does not need a separate helping verb like is here.

Because Arabic does not use an extra word like is in this kind of present-tense sentence.

English says:

• The boy is joking

Arabic simply says:

• يمزح الولد

The verb itself already carries the meaning of the action in the present. So يمزح can naturally mean is joking without any extra word.

الـ is the Arabic definite article, meaning the.

So:

• الولد = the boy
• ولد = a boy or just boy, depending on context

Since the sentence uses الولد, it is talking about a specific boy: the boy.

Because tanween normally appears on indefinite nouns, and الولد is definite because it has الـ.

So:

• ولدٌ = a boy
• الولدُ = the boy

Definite nouns do not take tanween.

Also, صديقي does not take tanween either, because nouns with attached possessive suffixes like -ي are also not indefinite.

In ordinary Arabic writing, the case endings are usually not written.

If you fully vocalize the sentence, you get:

يَمْزَحُ الْوَلَدُ مَعَ صَدِيقِي

Grammatically:

• يمزحُ ends in -u
• الولدُ is the subject, so it is nominative
• مع is a preposition
• the noun after مع is genitive

So صديقي is grammatically genitive after مع, even though the genitive ending is not separately visible in the usual written form because of the attached -ي.

مع means with.

It is a preposition, and the noun after it is put in the genitive case.

So:

• مع صديقي = with my friend

With the verb يمزح, مع gives the sense of joke with or be joking with someone.

The base noun is:

• صديق = friend

Arabic often adds possessive pronouns directly to the end of a noun. Here:

• -ي = my

So:

• صديقي = my friend

This is much more common in Arabic than using a separate word for my.

Normally صديق is masculine, so صديقي usually means my male friend.

If you want to say my female friend, you would usually say:

صديقتي

So the sentence as written normally suggests that the friend is male.

Yes, absolutely.

Both are grammatical:

• يمزح الولد مع صديقي
• الولد يمزح مع صديقي

The first is more typical verb-first MSA style.
The second is subject-first and can sound slightly more topical or emphatic, as if you are specifically talking about the boy.

Usually it suggests friendly joking.

So the sentence most naturally means that the boy is joking around with your friend.

If you want the stronger idea of mocking or making fun of, Arabic often uses a different expression, such as:

يسخر من

So the tone of يمزح مع is usually lighter and more playful.