يقرأ صديقي بقية الكتاب.

A word-by-word breakdown is:

• يقرأ = he reads / he is reading
• صديقي = my friend
• بقية = the rest / the remainder
• الكتاب = the book

So the full sentence means My friend is reading the rest of the book or My friend reads the rest of the book, depending on context.

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

So:

• يقرأ صديقي بقية الكتاب = My friend is reading the rest of the book

This is a very normal VSO pattern:

• Verb: يقرأ
• Subject: صديقي
• Object: بقية الكتاب

You can also say:

• صديقي يقرأ بقية الكتاب

That is also correct, but it gives the sentence a slightly different feel, with more focus on my friend.

In Arabic, the imperfect/present form often covers both:

• habitual action: he reads
• action happening now: he is reading

So يقرأ can mean either one. Context tells you which is meant.

For example:

• In a general description: My friend reads the rest of the book every night
• In a current situation: My friend is reading the rest of the book right now

Arabic usually does not need a separate form like English is reading.

Because the ending -ي on صديق means my.

• صديق = friend
• صديقي = my friend

This -ي is a attached possessive pronoun.

Other similar examples:

• كتابي = my book
• أخي = my brother
• بيتي = my house

So صديقي is literally friend-my, which in English becomes my friend.

بقية الكتاب is a very common Arabic structure called iḍāfa (the construct phrase).

It is made of:

• بقية = remainder / rest
• الكتاب = the book

Together:

• بقية الكتاب = the rest of the book

Arabic often expresses of relationships by placing two nouns together, without a separate word for of.

So instead of saying the rest of the book with an explicit of, Arabic says:

• بقية الكتاب
• literally: remainder the-book

This is because بقية الكتاب is an iḍāfa phrase.

In an iḍāfa:

• the first noun usually does not take ال
• the second noun can make the whole phrase definite

So:

• بقية كتاب = the rest of a book / a remainder of a book (indefinite sense)
• بقية الكتاب = the rest of the book (definite)

Even though بقية does not have ال, the whole phrase is definite because الكتاب is definite.

Because the subject صديقي is singular: my friend.

So Arabic uses:

• يقرأ = he reads / is reading

If the subject were dual or plural, the verb could change. For example:

• يقرأ الصديق = the friend reads
• يقرأ الصديقان = the two friends read
• يقرأ الأصدقاء = the friends read in normal VSO structure, the verb often stays singular when it comes first

This is an important point in Arabic: in verb-first sentences, the verb often agrees fully in gender but not always in full number the way English learners might expect.

In full vocalization, it would be:

• يقرأُ صديقي بقيةَ الكتابِ

Here is why:

• يقرأُ: the verb ends with -u
• صديقي: the subject is nominative
• بقيةَ: it is the direct object, so it takes the accusative
• الكتابِ: as the second word in the iḍāfa, it is genitive

So grammatically:

• صديقي = subject
• بقيةَ الكتابِ = object phrase

In normal everyday writing, these short vowel endings are usually not written.

Yes, absolutely.

Both are correct:

• يقرأ صديقي بقية الكتاب
• صديقي يقرأ بقية الكتاب

The difference is mainly word order and emphasis.

• يقرأ صديقي... is a normal verb-first MSA style
• صديقي يقرأ... puts more attention on my friend

English speakers often find the second one more familiar because English usually starts with the subject.

It is one common word for that meaning, but not the only possibility.

بقية often means:

• remainder
• rest
• what is left

So:

• بقية الكتاب = the rest of the book
• بقية اليوم = the rest of the day
• بقية الطلاب = the rest of the students

Depending on context, Arabic may also use other expressions, but بقية is very common and useful.

A careful pronunciation is approximately:

• yaqraʾu ṣadīqī baqiyyata l-kitābi

If you are reading normal unvocalized Arabic, you will usually just see:

• يقرأ صديقي بقية الكتاب

A few pronunciation notes:

• يقرأ contains ء at the end of the root sound sequence, so it is yaq-ra-ʾu
• ص is an emphatic s
• ق is a deep q sound, not like English k
• بقية is often pronounced baqiyya(tu/a) depending on case in formal reading

Because it is the thing being read.

In the sentence:

• يقرأ = is reading
• صديقي = the one doing the action
• بقية الكتاب = what is being read

So the structure is:

• Verb: يقرأ
• Subject: صديقي
• Object: بقية الكتاب

If the sentence were fully vocalized, the object marking would be clearer because بقية would be in the accusative:

• بقيةَ الكتابِ

That -a ending on بقيةَ helps show it is the direct object in formal grammar.