صديقي يحزم صندوق الكرتون.

صديقي = صديق + ـي

• صديق = friend
• ـي = my

So صديقي literally means my friend.

This ـي is an attached possessive pronoun. Arabic often shows possession by attaching a suffix directly to the noun, instead of using a separate word like my.

A few related examples:

• صديقه = his friend
• صديقتها = her friend
• صديقنا = our friend

Because the verb itself already tells you the subject.

In يحزم, the prefix يـ marks third person masculine singular, so the verb already means:

• he packs
• he is packing

That is why Arabic often does not need a separate pronoun like هو.

So:

• يحزم = he packs / he is packing
• هو يحزم = he is packing with extra emphasis on he

In your sentence, صديقي already names the subject, so no extra pronoun is needed.

يحزم comes from the verb حزم.

In this sentence, it means something like:

• packs
• is packing
• sometimes bundles up or ties up, depending on context

For a learner, the most natural meaning here is packs.

Also, in MSA the present tense often covers both:

• simple present: packs
• present progressive: is packing

So صديقي يحزم... can mean either My friend packs... or My friend is packing..., depending on context.

Yes. Arabic can use both:

• SVO: صديقي يحزم صندوق الكرتون
• VSO: يحزم صديقي صندوق الكرتون

Both are grammatical in MSA.

Very roughly:

• صديقي يحزم... puts a little more focus on my friend as the topic
• يحزم صديقي... starts more directly with the action

So the word order in your sentence is completely normal.

Because صندوق الكرتون is an iḍāfa construction, often called a construct phrase.

In an iḍāfa:

• the first noun comes first
• the second noun explains or limits it
• the first noun normally does not take ال

So:

• صندوق الكرتون = the cardboard box / box of cardboard

Here:

• صندوق = box
• الكرتون = the cardboard / cardboard

The first noun, صندوق, stays without ال because that is how iḍāfa works.

Yes, that is the basic structure.

Arabic often expresses relationships between nouns without using a separate word like of. Instead, it puts the nouns next to each other in an iḍāfa:

• صندوق الكرتون = box of cardboard
• more naturally in English: cardboard box

So the order is:

1. the main noun: صندوق
2. the specifying noun: الكرتون

That is why Arabic says the equivalent of box cardboard or box of cardboard, not cardboard box in English word order.

Grammatically, it is more naturally definite, because the second noun is الكرتون with ال.

In a regular iḍāfa, if the second noun is definite, the whole phrase is definite. So:

• صندوق الكرتون is grammatically like the cardboard box

However, in actual translation, English sometimes uses a cardboard box if the context is general rather than specific.

So the safest learner answer is:

• grammar: the cardboard box
• possible English translation depending on context: a cardboard box

If you wanted a more clearly indefinite expression, Arabic could also use: صندوقًا من الكرتون = a box made of cardboard

Because Arabic usually does not need one in this kind of phrase.

Instead of saying box of cardboard with a separate word for of, Arabic uses the iḍāfa pattern:

• صندوق الكرتون

This is one of the most common structures in Arabic.

Compare:

• باب البيت = the door of the house
• كتاب الطالب = the student’s book
• صندوق الكرتون = the cardboard box / box of cardboard

Arabic does have words like من that can sometimes mean of/from, but that gives a different structure:

• صندوق من الكرتون = a box made of cardboard

A fully vocalized version would be:

صَديقي يَحْزِمُ صُنْدوقَ الكَرْتونِ.

Here is the grammar:

• صديقي = subject
• يحزمُ = present tense verb in the indicative
• صندوقَ = direct object, so it is accusative
• الكرتونِ = genitive because it is the second noun in an iḍāfa

Notes:

• In normal Arabic writing, these short vowels are usually not written.
• At the end of a sentence, speakers often pause, and the very last case ending may not be pronounced in full.

Because the word has an attached possessive suffix: ـي = my.

When Arabic nouns take suffixes like this, the usual case ending is not shown in the simple way learners may expect. So even though صديقي is the subject, you do not see a clear final ـُ like you might with a fully separate noun.

That is normal.

So a learner should still understand صديقي as the subject from:

• its meaning
• its position in the sentence
• the overall sentence structure

A careful learner-style pronunciation is:

ṣadīqī yaḥzimu ṣundūqa al-kartūni

A few sounds may feel unfamiliar:

• ص in صديقي and صندوق
  This is an emphatic s, heavier than English s.

• ح in يحزم
  This is a stronger, breathier sound from the throat, not the normal English h.

• ق in صديقي and صندوق
  In careful MSA, this is q, pronounced far back in the mouth, not like k.

• Long vowels:

  • صديقي = ṣa-dī-qī
  • صندوق = ṣun-dūq
  • الكرتون = al-kar-tūn

If you say it slowly in chunks, it becomes easier:

• صديقي
• يحزم
• صندوق الكرتون