اول صفحة من الدفتر فيها اسمي.

In everyday Levantine, أول + noun is the normal way to say first + noun.

So:

• أول صفحة = the first page
• أول يوم = the first day
• أول مرة = the first time

The more formal / Standard Arabic style would be الصفحة الأولى. In colloquial speech, أول صفحة sounds much more natural.

Also, أول usually stays the same in this common colloquial pattern, even with a feminine noun like صفحة.

That is a very common colloquial pattern.

In Levantine, أول صفحة can already mean the first page, even without الـ on صفحة. The phrase is understood as definite from:

• the use of أول
• the context
• the rest of the phrase, especially من الدفتر

So أول صفحة من الدفتر naturally means the first page of the notebook.

If you were speaking more formally, you would be more likely to hear الصفحة الأولى من الدفتر.

Yes, من basically means from, but Arabic also uses it in part-whole expressions.

So:

• صفحة من الدفتر literally = a page from the notebook
• natural English meaning = a page of the notebook

This is very normal in Levantine. It is similar to saying one page from the book in English, where from still makes sense even though of may sound more natural in translation.

فيها is made of:

• في = in
• ها = it / her for a feminine noun

So فيها literally means in it.

Here it refers to صفحة, which is feminine, so:

• فيها اسمي = my name is in it
• natural English = my name is on it

With things like pages, notebooks, texts, or documents, Arabic often uses في where English would often say on.

Because the pronoun refers to صفحة, not to دفتر.

• صفحة is feminine
• دفتر is masculine

So the sentence is talking about the page, and that is why the attached pronoun is feminine:

• فيها = in/on it for a feminine noun

If it referred to الدفتر, you would expect فيه instead.

Because Arabic usually leaves out the present-tense verb to be.

So instead of saying:

• The first page of the notebook is ...
• My name is on it

Arabic often just puts the parts next to each other:

• أول صفحة من الدفتر = the first page of the notebook
• فيها اسمي = my name is on it

This is called a nominal sentence. It is completely normal in Arabic.

If you wanted past tense, then a verb like كان could appear.

اسمي is:

• اسم = name
• ـي = my

So:

• اسم
  • ـي = اسمي
• meaning: my name

Arabic usually shows possession by attaching a pronoun directly to the noun, instead of using a separate word like my.

Other examples:

• كتابي = my book
• بيتي = my house
• رقمي = my number

Both orders can be understandable, but فيها اسمي is very natural here.

The sentence first introduces the topic:

• أول صفحة من الدفتر

Then it comments on that topic:

• فيها اسمي

This gives a sense like:

• As for the first page of the notebook, my name is on it

Putting فيها first makes the location sound prominent.
If you said اسمي فيها, that could also work, but it may sound a bit different in emphasis.

Arabic word order is often flexible, especially in spoken dialects.

Yes, you may hear that too.

• عليها = on it
• فيها = literally in it, but often naturally used for written content on a page

So both can make sense, but they are not always felt in exactly the same way.

A rough difference:

• فيها اسمي can feel like my name is written in/on it as part of what the page contains
• عليها اسمي can feel more literally my name is on it

In real speech, both are possible depending on speaker and context, but فيها اسمي is very natural.

A helpful pronunciation is:

awwal safḥa mn id-daftar fīha ismi

A few notes:

• أول = awwal
• صفحة = safḥa or more accurately ṣafḥa
  The ص is a heavier, emphatic s
• من is often reduced in speech to mn
• الدفتر is often pronounced id-daftar or ed-daftar
  because د is a sun letter, so the l of الـ assimilates
• فيها = fīha, with a long ee
• اسمي = ismi

So in fast speech it may sound something like:

awwal safḥa mn id-daftar fīha ismi