الكتاب ده قديم.

A common Egyptian pronunciation is el-ketāb da ʾadīm.

A few notes:

• الكتاب is often said as el-ketāb
• ده is da
• قديم is often ʾadīm in Cairo-style speech, because ق is commonly pronounced as a glottal stop

So although it is written قديم, many Egyptians do not say qadīm in everyday speech. Some speakers and regions do keep a real q sound, though.

ده is the Egyptian Arabic masculine singular demonstrative, meaning this.

In Egyptian Arabic, when a demonstrative goes with a noun, it usually comes after the noun:

• الكتاب ده = this book
• الولد ده = this boy

This is different from English, where this comes before the noun.

In Arabic, the present-tense verb to be is usually omitted.

So الكتاب ده قديم is literally something like the-book this old, but it naturally means this book is old.

This is very normal in both Egyptian Arabic and Modern Standard Arabic for present-tense sentences like:

• هو تعبان = he is tired
• الجو حلو = the weather is nice

If you want past or future, you usually do need an actual verb, such as كان for was.

الـ is the Arabic definite article, like the in English.

So كتاب means a book or just book, while الكتاب means the book.

In Egyptian Arabic, when you say this + noun, the noun is normally definite:

• الكتاب ده = this book
• not normally كتاب ده

So the الـ is part of the normal pattern for noun + demonstrative in Egyptian Arabic.

Because قديم is not being used as the old inside a noun phrase. It is the predicate of the sentence.

Compare these:

• الكتاب القديم = the old book
  Here قديم is directly describing the noun inside the noun phrase, so it becomes definite too: القديم

• الكتاب ده قديم = this book is old
  Here قديم is what is being said about the book, so it stays indefinite in form

This is a very important Arabic pattern:

• attributive adjective: matches definiteness
• predicate adjective: usually does not take الـ

Yes. كتاب is a masculine singular noun, so the other words agree with it.

That is why you get:

• ده for masculine singular
• قديم for masculine singular

If the noun were feminine, the forms would change:

• القصة دي قديمة = this story is old

So Egyptian Arabic shows agreement in gender, and often number too.

Not in this sentence if you want the usual Egyptian Arabic way to say this book.

The normal Egyptian pattern is:

• الكتاب ده

If you put ده first, you usually get a different structure:

• ده كتاب قديم = this is an old book

So:

• الكتاب ده قديم = this book is old
• ده كتاب قديم = this is an old book

Both are correct, but they do not have the same grammar.

A typical Modern Standard Arabic version would be:

هذا الكتاب قديم

The main differences are:

• MSA usually puts the demonstrative before the noun: هذا الكتاب
• Egyptian Arabic usually puts it after the noun: الكتاب ده
• Egyptian Arabic uses colloquial forms like ده
• Everyday Egyptian pronunciation is also different from formal pronunciation

So this sentence is a good example of a very common Egyptian structure.

To negate it in Egyptian Arabic, you usually use مش:

الكتاب ده مش قديم = this book is not old

To make it a question, you can often just use rising intonation:

الكتاب ده قديم؟ = Is this book old?

You can also say:

هو الكتاب ده قديم؟

That sounds like Is this book old? too, with a bit more explicit question marking in speech.