هؤلاء في الحديقة العامة.

It is pronounced hāʾulāʾi.

A simple learner-friendly breakdown is:

• hā
• ʾu
• lā
• ʾi

So there is a glottal stop (hamza) after the first long ā, and another one near the end. In careful MSA pronunciation, both hamzas are heard.

هؤلاء is the plural near demonstrative, meaning these.

A few useful points:

• It is used for plural nouns.
• It does not change for masculine vs. feminine in the plural.
• So it can refer to:
  • these men
  • these women
  • these people
  • a mixed group

In this sentence, it stands on its own, like these in English.

In present-tense Arabic, sentences like this often do not use a separate verb for is/am/are.

So:

• هؤلاء في الحديقة العامة
  literally looks like These in the public garden
• but naturally means These are in the public garden or These are in the public park

This is called a nominal sentence. In the present tense, Arabic usually leaves out the copula are.

If you wanted past tense, you would normally use كان or a related form.

Because Arabic demonstratives can work by themselves, not only before a noun.

So:

• هؤلاء = these
• هؤلاء الطلاب = these students

Both are correct. In your sentence, the noun is simply understood from context.

The sentence is a basic nominal sentence:

• هؤلاء = the topic / subject-like element (mubtadaʾ)
• في الحديقة العامة = the predicate / comment about it (khabar)

So the structure is:

• These
• are in the public garden/park

A prepositional phrase like في الحديقة العامة can serve as the predicate in Arabic.

Because العامة is an adjective describing الحديقة, and in Arabic adjectives must match the noun in definiteness.

So:

• الحديقة = the garden / the park
• العامة = the public

Together:

• الحديقة العامة = the public garden / the public park

If the noun is definite, the adjective must also be definite.

Compare:

• الحديقة العامة = the public garden
• حديقة عامة = a public garden

No. It is not an iḍāfa; it is a noun + adjective phrase.

Why?

• The adjective العامة comes after the noun.
• It matches the noun in:
  • definiteness
  • gender
  • number
  • case

That is the normal behavior of adjectives in Arabic.

An actual iḍāfa would look different, for example something like حديقة المدينة = the city’s garden / the city park.

So here:

• الحديقة العامة = noun + adjective
• not possessive, not iḍāfa

Because it is describing الحديقة, and حديقة is a feminine singular noun.

Arabic adjectives agree with the nouns they describe. So العامة must match الحديقة in:

• gender: feminine
• number: singular
• definiteness: definite
• case: here, genitive because of في

That is why you get:

• الحديقة العامة
• not الحديقة العام
• and not الحديقة العامون, etc.

After the preposition في, the following noun is in the genitive case.

So in fully vowelled Arabic, this would be:

• في الحديقةِ العامةِ

Both words take genitive because:

• الحديقةِ is governed by في
• العامةِ follows it as an adjective, so it matches its case

A fully vowelled version of the whole sentence is:

• هؤلاءُ في الحديقةِ العامةِ

In everyday reading and speech, learners often see or hear it without the case endings.

In very careful formal MSA, yes, you may pronounce them:

• هؤلاءُ في الحديقةِ العامةِ

But in much real-life formal speech, news-style reading, and learner speech, the final case vowels are often softened or omitted.

So you will commonly hear something closer to:

• هؤلاء في الحديقة العامة

Both are understandable, but the fully inflected version is the grammatically complete one.

Yes, but the given order is the most neutral and straightforward.

The normal version here is:

• هؤلاء في الحديقة العامة

This starts with the topic هؤلاء, then gives information about them.

Arabic can sometimes move the prepositional phrase forward for emphasis or context, but for a learner, this sentence is the best basic pattern to remember:

• demonstrative/topic + prepositional phrase

So this sentence is a very useful model for saying where someone or something is.