يفك صديقي الشفرة ويحل الأحجية.

With full short vowels, it is:

يَفُكُّ صَدِيقِي الشِّفْرَةَ وَيَحُلُّ الأُحْجِيَّةَ

A helpful transliteration is:

yafukku ṣadīqī ash-shifrata wa yaḥullu al-uḥjiyyata

In normal reading or speaking, the final case vowels are often not pronounced in pause, so you may hear something closer to:

yafukku ṣadīqī ash-shifra wa yaḥullu al-uḥjiyya

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

So this sentence is:

• يفك = cracks/deciphers
• صديقي = my friend
• الشفرة = the code

This word order is completely normal in MSA.

You can also say:

صديقي يفك الشفرة ويحل الأحجية

That version is also correct, but it puts a little more focus on my friend.

The -ي means my.

• صديق = friend
• صديقي = my friend

Arabic often shows possession by adding a suffix directly to the noun, instead of using a separate word like my.

So صديقي is literally friend-my, but in natural English it means my friend.

They are in the imperfect form, which in this context usually gives a present meaning:

• يفك = he cracks / he is cracking
• يحل = he solves / he is solving

In MSA, this form can also express habitual actions or sometimes future meaning if the context makes that clear. But here the most natural reading is simple present: he cracks ... and solves ...

The forms يفك and يحل are 3rd person masculine singular here, so they mean he cracks and he solves.

That matches the subject صديقي because صديق is a masculine noun.

Arabic often does not need a separate word for he if the verb form already shows it.

Because و meaning and is written as a prefix in Arabic.

So:

• و = and
• يحل = he solves
• ويحل = and he solves

This is very common. Short particles like و are often attached directly to the following word.

This is because of sun letters and moon letters.

In الشفرة, the letter ش is a sun letter, so the ل of ال is not pronounced separately. Instead, it assimilates:

• الشفرة is pronounced ash-shifra

In الأحجية, the next sound is not a sun letter, so ال keeps its normal pronunciation:

• الأحجية is pronounced al-uḥjiyya

So the spelling stays ال in both words, but the pronunciation changes depending on the next letter.

Because the basic verbs are:

• فكّ = to undo, unfasten, crack, decipher
• حلّ = to solve, untie

These are called geminate or doubled verbs: the last root consonant is doubled.

The shadda shows that doubling:

• يفكّ = ya-fukk
• يحلّ = ya-ḥull

That doubling is part of the verb itself, not just a spelling detail.

Because they are direct objects, so in full formal Arabic they take the accusative ending:

• الشِّفْرَةَ
• الأُحْجِيَّةَ

They are the things being acted on:

• he cracks the code
• he solves the riddle

In ordinary Arabic writing, these short case endings are usually omitted, which is why you normally see:

• الشفرة
• الأحجية

It is the subject, so it is nominative.

However, with a noun plus the -ي possessive suffix, the case ending is not clearly visible in the usual form. So even though صديقي is nominative here, you do not see a separate nominative ending the way you might with other nouns.

This is a common feature of nouns with my attached.

Because both words have ال, which means the:

• الشفرة = the code
• الأحجية = the riddle

This suggests a specific code and a specific riddle.

Arabic could also make them indefinite if the context required it, but here the definite form sounds natural and complete.

It belongs to both verbs.

The structure is:

• يفك صديقي الشفرة
• ويحل الأحجية

The subject صديقي is understood with both actions:

My friend cracks the code and solves the riddle.

Arabic does not need to repeat صديقي before the second verb unless the speaker wants extra emphasis.