هذا جهاز جديد.

In Arabic, the verb to be is usually not expressed in the present tense.

So Arabic says:

• هذا جهاز جديد
• literally: this device new
• natural English: This is a new device

This kind of sentence is called a nominal sentence. Arabic often links the subject and predicate without a present-tense is/are.

If you wanted a past or future meaning, then Arabic would use a verb, for example:

• كان هذا جهازًا جديدًا = This was a new device
• سيكون هذا جهازًا جديدًا = This will be a new device

A simple breakdown is:

• هذا = this
• جهاز = device / apparatus / machine
• جديد = new

Grammatically:

• هذا is the subject: this
• جهاز جديد works as the predicate: a new device

So the whole sentence means:

• This is a new device

In other words, Arabic is not saying this new device here. It is making a complete statement: This is a new device.

Because جهاز is a masculine singular noun.

In Arabic, the demonstrative has to match the gender and number of what you are pointing to:

• هذا = this for masculine singular
• هذه = this for feminine singular

Since جهاز is masculine, you say:

• هذا جهاز جديد

If the noun were feminine, you would say something like:

• هذه سيارة جديدة = This is a new car

Because the sentence means This is a new device, not This is the new device.

In Arabic:

• جهاز جديد = a new device (indefinite)
• الجهاز الجديد = the new device (definite)

So:

• هذا جهاز جديد = This is a new device
• هذا الجهاز الجديد can mean This is the new device or this new device, depending on context

A key point: after هذا at the beginning of a full sentence, Arabic can use an indefinite predicate like جهاز جديد.

Because in Arabic, adjectives normally come after the noun they describe.

So:

• جهاز جديد = literally device new
• natural English: new device

This is the normal Arabic order:

• noun + adjective

Examples:

• كتاب كبير = a big book
• بيت جميل = a beautiful house
• جهاز جديد = a new device

Arabic adjectives agree with the noun they describe in several ways, including:

• gender
• number
• definiteness
• usually also case in fully vocalized Arabic

Here, جهاز is:

• masculine
• singular
• indefinite

So the adjective must match that:

• جديد = masculine singular indefinite

Compare:

• جهاز جديد = a new device
• السيارة الجديدة = the new car
  Here the adjective changes because سيارة is feminine and definite.

In careful Modern Standard Arabic, it is pronounced approximately:

• hādhā jihāz jadīd

If full case endings are pronounced in formal reading, it would be:

• hādhā jihāzun jadīdun

A few pronunciation notes:

• هذا = hādhā
  The ذ sounds like the th in this
• جهاز = jihāz
  The ج in MSA is usually like English j in jam
• جديد = jadīd
  The last syllable has a long ee sound

In fully vocalized MSA, you would usually write:

• هٰذا جِهَازٌ جَدِيدٌ

or more commonly without the dagger alif marking:

• هذا جهازٌ جديدٌ

The endings -ٌ on جهازٌ and جديدٌ are the indefinite nominative endings.

However, in normal everyday writing, Arabic usually omits these short vowels, so you most often see:

• هذا جهاز جديد

Also, when pausing at the end of a sentence, many speakers do not pronounce the final case ending clearly.

This is a very important distinction.

1. هذا جهاز جديد

This is a complete sentence:

• This is a new device

Here, جهاز جديد is indefinite.

2. هذا الجهاز الجديد

This can be understood as:

• This is the new device or
• this new device

depending on context and how it is used.

The noun and adjective are both definite:

• الجهاز = the device
• الجديد = the new

So the presence or absence of الـ changes the meaning a lot.

You would say:

• هذا الجهاز الجديد

Why? Because this new device is a noun phrase, not a full sentence.

Arabic usually forms this + noun + adjective as:

• هذا
  • definite noun
    • definite adjective

So:

• هذا الجهاز الجديد = this new device

But:

• هذا جهاز جديد = This is a new device

That contrast is one of the most useful things to notice in this example.

You would change the demonstrative and the adjective form as needed.

Feminine singular

• هذه سيارة جديدة = This is a new car

Changes:

• هذا → هذه
• جديد → جديدة

Masculine plural

• هذه أجهزة جديدة = These are new devices

In MSA, non-human plurals like أجهزة often take feminine singular agreement with demonstratives and adjectives, so:

• هذه (not هؤلاء)
• جديدة (not masculine plural)

That point can feel surprising to English speakers, but it is normal in Arabic for many non-human plurals.

Yes. هذا often works very much like English this.

It can point to:

• something physically near
• something just mentioned
• something being introduced in discourse

So هذا جهاز جديد could be used when someone is showing you a device and saying:

• This is a new device

Arabic demonstratives are very common and useful, but they must agree with the noun in gender and number more consistently than English does.