صديقي يتأمل المجموعة الأثرية في الجولة الذاتية.

صديقي is made of:

• صديق = friend
• ـي = my

So صديقي literally means friend-my, i.e. my friend.

Arabic often shows possession by attaching a pronoun suffix directly to the noun. Once that suffix is attached, the noun is already definite, so you do not add الـ. That is why you say صديقي, not الصديقي.

Yes. صديق is grammatically masculine, so صديقي normally means my male friend.

If you wanted my female friend, you would say صديقتي.

Arabic allows more than one normal word order.

• صديقي يتأمل...
• يتأمل صديقي...

Both are possible. Starting with صديقي gives the subject a bit more prominence, like My friend is the one who... or simply a more topic-first style.

In traditional grammar, a sentence that begins with a noun like this is often analyzed as:

• صديقي = the topic / mubtadaʾ
• يتأمل المجموعة الأثرية... = the comment about it

For a learner, it is fine to think of it as subject-first word order.

يتأمل is a present/imperfect verb, 3rd person masculine singular.

That means it matches he:

• هو يتأمل = he contemplates / he is observing

So with صديقي, it agrees with a singular masculine subject.

Depending on context, the Arabic present can mean either:

• contemplates / observes
• is contemplating / is observing

A fully vowelled version is:

صَديقي يَتَأَمَّلُ المَجْمُوعَةَ الأَثَرِيَّةَ في الجَوْلَةِ الذَّاتِيَّةِ

A helpful transliteration is:

ṣadīqī yataʾammalu al-majmūʿata al-athariyyata fī al-jawlati adh-dhātiyyati

A few pronunciation notes:

• يَتَأَمَّلُ has a hamza in the middle: yata-ʾammalu
• الذَّاتِيَّةِ is pronounced with assimilation: adh-dhātiyyati, not al-dh...

In Arabic, descriptive adjectives usually come after the noun they describe.

So:

• المجموعة الأثرية = literally the collection archaeological
• الجولة الذاتية = literally the tour self-guided

This is just normal Arabic adjective position.

Because Arabic adjectives agree with the nouns they describe in definiteness.

So if the noun is definite, the adjective must also be definite:

• المجموعة الأثرية = the archaeological collection

If the noun were indefinite, the adjective would also be indefinite:

• مجموعة أثرية = an archaeological collection

The same pattern appears in الجولة الذاتية.

Because Arabic adjectives must agree with the noun in gender and number.

Here:

• مجموعة is feminine singular, so its adjective is أثرية
• جولة is also feminine singular, so its adjective is الذاتية

That is why you do not get masculine forms like أثري or ذاتي here.

Because it comes after the transitive verb يتأمل, and it is the thing being contemplated/observed.

In fully vowelled formal Arabic, the object would show the accusative case:

• المجموعةَ الأثريةَ

In normal Arabic writing, short vowels are usually omitted, so you do not see those endings. But grammatically, it is still the direct object.

في literally means in, but in many contexts it can also mean something like:

• during
• on
• in the course of
• as part of

So in this sentence, في الجولة الذاتية is naturally understood as something like during / on the self-guided tour, not only physical location inside something.

Because ذ is a sun letter.

When الـ comes before a sun letter, the l sound assimilates to the next consonant. So:

• written: الذاتية
• pronounced: adh-dhātiyya

In fully vowelled text, that doubling is shown with a shadda on ذ:

• الذَّاتية

The spelling stays the same, but the pronunciation changes.