يذهب صديقي إلى النادي.

• يذهب is the verb: goes / is going
• صديقي is the subject: my friend
• إلى النادي is a prepositional phrase: to the club

So the structure is basically goes + my friend + to the club.

Because Arabic very often uses verb-first word order, especially in Modern Standard Arabic.

So يذهب صديقي إلى النادي is a normal VSO sentence: Verb + Subject + Object/Complement.

You can also say صديقي يذهب إلى النادي, which is SVO order. Both are correct, but the verb-first version is very common in formal Arabic.

Arabic verbs usually include information about the subject.
يذهب by itself means he goes / he is going.

When صديقي is added, Arabic is not being redundant in a wrong way; it is simply making the subject explicit:

• يذهب = he goes
• يذهب صديقي = my friend goes

This is completely normal in Arabic.

يذهب is in the imperfect form. In this sentence, it usually gives a present meaning such as:

• goes
• is going
• sometimes does go

Depending on context, the imperfect can also refer to the future, but if you want a clearly marked future, Arabic often uses سـ or سوف, for example سيذهب = he will go.

It is made of:

• صديق = friend
• ـي = my

So:

• صديق = friend
• صديقي = my friend

This ـي is a possessive suffix attached directly to the noun.

Because a noun with a possessive suffix is already definite.

So Arabic does not say the my friend.
It simply says صديقي, which already means my friend and is automatically definite.

This is similar to how English says my friend, not the my friend.

إلى is the preposition that means to or toward.

So:

• يذهب إلى... = goes to...

It is the natural preposition to use with a destination in a sentence like this.

Also, إلى makes the following noun genitive in Arabic grammar.

Good question. Grammatically, النادي is indeed genitive after إلى.

However, this noun ends in -ي, and in this kind of word the case ending is often not visibly pronounced or written in the usual way. So the genitive is there grammatically, even though the word still looks like النادي.

This is one reason Arabic case can feel less obvious in unvocalized text.

It is pronounced an-nādī, not al-nādī.

That is because ن is a sun letter. When ال comes before a sun letter, the ل sound assimilates into the next consonant.

So:

• النادي
• pronounced an-nādī

In careful writing, this is often reflected by the shadda on ن: النَّادِي.

Yes, absolutely.

Both are correct:

• يذهب صديقي إلى النادي
• صديقي يذهب إلى النادي

The first one is more characteristically formal Arabic word order (verb first).
The second one may feel a bit more like My friend goes to the club, with the subject presented first.

With this singular subject, the meaning stays basically the same.

A commonly vowelled version is:

يَذْهَبُ صَدِيقِي إِلَى النَّادِي

This shows:

• يَذْهَبُ = the verb with its vowel pattern
• إِلَى = the preposition
• النَّادِي = with the sun-letter pronunciation shown by the shadda

Even with full vowel marks, صديقي and النادي do not show their case in an obvious way here, although grammatically صديقي is the subject and النادي is genitive after إلى.