جدي في البيت.

A common Egyptian pronunciation is giddi fil-bēt.

• ج is usually pronounced g in Egyptian Arabic, not j.
• جدي sounds like gid-di.
• في البيت is usually linked together in speech as fil-bēt.
• بيت is often pronounced bēt in Egyptian, with a long ē sound.

A rough stress pattern is: GID-di fil-BEET.

Because Arabic usually drops the verb to be in the present tense.

So جدي في البيت is literally something like:

• my grandfather
• in the house / at home

But it naturally means My grandfather is at home.

This kind of sentence is very normal in Arabic.

The ـي is the suffix for my.

So:

• جد = grandfather
• جدي = my grandfather

Arabic often attaches possessive words like my, your, or his directly to the noun instead of using a separate word.

That is a well-known feature of Egyptian Arabic.

In Modern Standard Arabic, ج is usually pronounced more like j in jam.
In Egyptian Arabic, it is usually pronounced g as in go.

So:

• Standard Arabic pronunciation: jaddī
• Egyptian pronunciation: giddi or gaddi, depending on the speaker and context

For an Egyptian learner, g is the important sound to remember.

Because في البيت can mean both:

• in the house
• at home

In many everyday situations, Arabic uses the house where English prefers home.

So in this sentence, جدي في البيت is very naturally understood as My grandfather is at home.

Arabic often uses the definite article الـ in places where English does not.

So:

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

Even though English says at home without the, Arabic normally says في البيت. That is just the natural Arabic pattern.

No. You do not need it here.

جدي already tells you who the subject is: my grandfather.

So:

• جدي في البيت = correct and natural
• adding هو is usually unnecessary here

Arabic often leaves out subject pronouns when the noun itself is already present.

Yes, but جدي في البيت is the most neutral and straightforward order.

This sentence is:

• جدي = the topic / subject
• في البيت = where he is

You may also hear the place come first for emphasis, but that changes the feel of the sentence. For a learner, جدي في البيت is the best version to use first.

In Egyptian Arabic, you can say:

جدي مش في البيت

Pronounced: giddi mish fil-bēt

Here:

• مش = not / isn’t

So:

• جدي في البيت = My grandfather is at home
• جدي مش في البيت = My grandfather isn’t at home

The written sentence جدي في البيت works in both Standard Arabic and Egyptian Arabic.

The main difference is pronunciation:

• Standard Arabic: jaddī fī l-bayt
• Egyptian Arabic: giddi fil-bēt

So the structure and meaning are fine in both, but an Egyptian speaker will pronounce it in the Egyptian way.