يأكل صديقي الحلوى.

A careful reading is:

yaʾkulu ṣadīqī al-ḥalwā

A few pronunciation notes:

• يأكل = yaʾkulu
  The ʾ shows a hamza, a small catch in the voice.
• ص in صديقي is an emphatic s sound.
• ح in الحلوى is a deeper, breathier h than English h.
• The final ى in الحلوى is pronounced like a long ā.

So the last word sounds like al-ḥalwā.

Because Modern Standard Arabic often uses verb–subject–object order.

So the sentence is literally:

eats my friend the candy

That is normal in Arabic. You can also say:

صديقي يأكل الحلوى

That version is also correct, but it puts more focus on my friend as the topic.

يأكل is the imperfect form of the verb to eat.

Here it means:

• he eats
• he is eating

The exact English translation depends on context. Arabic does not need a separate word like does or is here.

Grammatically, يأكل is:

• 3rd person
• masculine
• singular

Because صديقي means my friend, and صديق is a masculine noun.

So the verb matches a masculine singular subject:

• يأكل = he eats

If the subject were feminine, you would say:

تأكل صديقتي الحلوى
My female friend eats the candy.

It is made of two parts:

• صديق = friend
• ـي = my

So:

صديقي = my friend

In Arabic, possessive words like my, your, and his are often attached directly to the noun as suffixes.

Because صديقي is already definite.

A noun with a possessive suffix, like ـي meaning my, is automatically specific:

• صديق = a friend / friend
• صديقي = my friend

So Arabic does not say الصديقي in this meaning.

حلوى can mean:

• sweets
• candy
• dessert

With الـ, it becomes definite:

الحلوى = the sweets / the candy / the dessert

Depending on context, Arabic may use a definite noun where English might say either the candy or just candy.

Also, the final ى is called alif maqṣūra, and it sounds like a long ā.

Yes, in fully vocalized MSA you could write it as:

يَأْكُلُ صَدِيقِي الْحَلْوَى

Grammatically:

• يأكلُ is the verb
• صديقي is the subject
• الحلوى is the object

In normal Arabic writing, short vowels are usually omitted, so learners often do not see the case endings clearly.

Also, in this particular sentence the endings are less obvious because:

• صديقي ends with the possessive -ī
• الحلوى ends in ى

So even though case is part of the grammar, it is not very visible here on the page.