عندي تلات كتب في البيت.

A common Egyptian pronunciation is:

ʿandi talat kotob fil-bēt

A few notes:

• ع in عندي is the Arabic letter ʿayn, a sound English does not really have.
• تلات is talat in everyday speech.
• كتب here is pronounced kotob in Egyptian Arabic.
• في البيت is usually said together as fil-bēt.

So the rhythm is roughly: ʿAN-di ta-LAT ko-TOB fil-BEET.

عندي literally means something like at me or with me.

It is made of:

• عند = at / by / with
• -ي = my / me

In Egyptian Arabic, this is a very common way to express possession. So instead of using a verb like have, Arabic often says:

• عندي = I have
• عندك = you have
• عنده = he has
• عندها = she has

So عندي تلات كتب is literally closer to At me are three books, but naturally it means I have three books.

Because Egyptian Arabic usually does not use a normal verb equivalent to English have in sentences like this.

Instead, possession is usually expressed with words like:

• عند = for temporary/general possession, availability
• مع = with me/on me, often for things physically with someone

So:

• عندي تلات كتب = I have three books
• معايا تلات كتب = I have three books with me / on me

In your sentence, عندي is the natural choice because the books are something the speaker owns or has, and then في البيت tells you where they are.

Because this sentence is in Egyptian Arabic, not formal Modern Standard Arabic.

Compare:

• ثلاثة = the formal/MSA form
• تلاتة / تلات = the Egyptian form

Two important dialect changes are happening:

• ث often becomes ت in Egyptian speech
• the word is shortened in everyday usage

So تلات is a normal Egyptian way to say three.

Yes, many speakers do say تلاتة كتب, and many also say تلات كتب.

In everyday Egyptian Arabic, numbers are often shortened before a noun. So:

• تلاتة = full standalone form
• تلات = shortened form before a counted noun

That means both of these are natural:

• عندي تلات كتب
• عندي تلاتة كتب

The version in your sentence is very common in casual speech.

Because after numbers like three, Arabic normally uses a plural noun.

So:

• كتاب = book
• كتب = books

That is why the sentence says:

• تلات كتب = three books

This is different from English only in the details of how Arabic handles counting, but the basic idea is simple here: after three, you use books, not book.

Also, كتب is the normal plural of كتاب. It is a broken plural, which means Arabic changes the inside pattern of the word instead of just adding an ending.

Because Arabic script usually leaves out short vowels, so كتب can represent different words depending on context.

For example, the same letters could be read differently in other contexts. But here, the context makes it clear:

• it comes after تلات = three
• after a number, you expect a noun being counted
• so كتب here must mean books (kotob in Egyptian pronunciation)

So even though the spelling is the same, the sentence structure tells you what it means.

في البيت literally means in the house.

It breaks down as:

• في = in / at
• البيت = the house / the home

In Arabic, البيت often means home in the everyday sense, not just a physical house. So:

• في البيت can mean in the house
• but very often it simply means at home

That is why Arabic uses the here even when English normally says just home.

Also, in pronunciation:

• في البيت becomes fil-bēt

The word order is not completely fixed. The sentence as written is very natural:

عندي تلات كتب في البيت

This is a neutral way to say it.

But you can also say: في البيت عندي تلات كتب

That puts more focus on at home / in the house.

So:

• عندي تلات كتب في البيت = neutral statement
• في البيت عندي تلات كتب = emphasizes where the books are

Both are understandable and natural in Egyptian Arabic.

It is Egyptian Arabic.

Clues:

• تلات is Egyptian, not formal MSA
• the sentence has an everyday spoken feel

A more formal Modern Standard Arabic version would be:

• عندي ثلاثة كتب في البيت or even
• لدي ثلاثة كتب في البيت

So the meaning is the same, but the style is different:

• عندي تلات كتب في البيت = everyday Egyptian
• عندي ثلاثة كتب في البيت = more formal/standard Arabic