هاي سيارة جديدة.

هاي means this in Levantine Arabic.

In this sentence, it is the feminine singular form, because سيارة (car) is a feminine noun. So:

• هاي سيارة جديدة = This is a new car

In different parts of the Levant, you may also hear other forms such as هيدي or هادي with the same basic meaning.

In Arabic, especially in the present tense, you usually do not say a word for is / am / are in sentences like this.

So English:

• This is a new car

becomes Levantine Arabic:

• هاي سيارة جديدة

This is completely normal. Arabic simply leaves the present-tense to be unstated in this kind of sentence.

Because هاي سيارة جديدة means This is a new car.

Here, سيارة جديدة is an indefinite phrase:

• سيارة = a car
• جديدة = new

If you say هاي السيارة الجديدة, that means this new car as a noun phrase, not a full sentence in the same way.

Compare:

• هاي سيارة جديدة = This is a new car
• هاي السيارة الجديدة = this new car

So the version without الـ fits the meaning a new car.

In Arabic, adjectives normally come after the noun they describe.

So:

• سيارة جديدة = a new car
• literally: car new

This is the normal Arabic word order for noun + adjective.

Because adjectives in Arabic must agree with the noun they describe.

Since سيارة is:

• feminine
• singular
• indefinite

the adjective جديدة must also be:

• feminine
• singular
• indefinite

That is why you get:

• سيارة جديدة

not a masculine form like جديد.

Yes, سيارة is a grammatically feminine noun.

A very common clue is the ending ة (taa marbuuTa), which often marks feminine nouns. So learners quickly get used to treating سيارة as feminine, which is why it takes:

• the feminine demonstrative هاي
• the feminine adjective جديدة

A common Levantine-style pronunciation is:

• haay sayyaara jdeede

A few notes:

• هاي sounds like haay
• سيارة sounds roughly like say-yaa-ra
• جديدة in Levantine is often pronounced jdeede, not like the full Modern Standard Arabic pronunciation jadīda

So the rhythm is roughly:

• haay say-yaa-ra jdee-de

Usually, no. In this sentence, the final ة is pronounced like a short a or e sound, not like t.

So:

• سيارة → sayyaara
• جديدة → jdeede

The t sound can appear in some grammatical contexts, especially when a word is followed closely by another word in certain formal structures, but in a simple sentence like this, you normally do not pronounce it as t.

Yes. Levantine Arabic has regional variation.

Depending on the country, city, or speaker, you may hear:

• هاي
• هيدي
• هادي

All of these can mean this for a feminine noun. The exact form depends on the dialect. So if your course or teacher uses one of those instead of هاي, that is normal.

They are different sentences.

• هاي سيارة جديدة = This is a new car
• هاي السيارة جديدة = This car is new

Why?

In هاي سيارة جديدة, the speaker is identifying what something is: a new car.

In هاي السيارة جديدة, السيارة is definite: the car / this car, and جديدة tells you something about it: is new.

So the presence or absence of الـ changes the meaning quite a bit.

It is clearly Levantine-style Arabic.

A few clues:

• هاي is a colloquial Levantine demonstrative
• جديدة would often be pronounced jdeede in speech
• there are no case endings, which is normal in spoken Arabic

In Modern Standard Arabic, the equivalent would usually be:

• هذه سيارة جديدة

So this sentence is a natural spoken Levantine way to say it.