هذا اختبار نهائي.

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

So هذا اختبار نهائي literally looks like:

• هذا = this
• اختبار نهائي = a final exam

But the full meaning is:

• This is a final exam.

This is very normal in Modern Standard Arabic.
If you wanted past or future, Arabic would use a verb, but in the present tense it is usually omitted.

هذا means this for a masculine singular noun.

It is used here because اختبار is a masculine singular noun, so the correct demonstrative is هذا.

A few related forms are:

• هذا = this (masculine singular)
• هذه = this (feminine singular)
• هذان / هاتان = these two
• هؤلاء = these

So because اختبار is masculine, هذا is the right choice.

Because the sentence means This is a final exam, not This is the final exam.

In Arabic:

• اختبار نهائي = a final exam
• الاختبار النهائي = the final exam

Here, اختبار نهائي is indefinite, which matches the English meaning a final exam.

So the sentence structure is:

• هذا = this
• اختبار نهائي = a final exam

If you said هذا الاختبار النهائي, that would usually mean This is the final exam or this final exam, depending on context.

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

So:

• اختبار = exam/test
• نهائي = final

Together:

• اختبار نهائي = final exam

This is the normal Arabic order:

• noun + adjective

Compare:

• كتاب جديد = a new book
• طالب مجتهد = a hardworking student
• اختبار نهائي = a final exam

Yes. In Arabic, adjectives agree with the noun they describe in several ways, especially:

• gender
• number
• definiteness
• usually case as well

Here:

• اختبار is masculine singular and indefinite
• نهائي is also masculine singular and indefinite

So they match correctly.

That is why you get:

• اختبار نهائي

If the noun were definite, the adjective would also become definite:

• الاختبار النهائي = the final exam

A common pronunciation is:

hādhā ikhtibār nihāʾī

A few notes:

• هذا = hādhā
• اختبار begins with a vowel sound here: ikhtibār
• نهائي is pronounced approximately nihāʾī

The ء in نهائي is a hamza, so there is a small break in the middle of the word:
ni-hā-ʾī

If full case endings are pronounced in careful formal Arabic, it can be:

hādhā ikhtibārun nihāʾiyyun

But in normal pausal pronunciation, learners often hear:

hādhā ikhtibār nihāʾī

Because the initial ا in اختبار is part of a pattern that is commonly pronounced with i at the beginning in citation form:

• اختبار = ikhtibār

This word comes from the verb اختبر (ikhtabara), meaning to test.
So اختبار is the verbal noun, meaning testing or test/exam depending on context.

For a learner, the important thing is simply to remember:

• اختبار = ikhtibār

It can mean either test or exam, depending on context.

• اختبار is a general word for a test/exam
• امتحان is another very common word, often also meaning exam

In many contexts, both can be used, though usage can vary by region and situation.

In this sentence, because of نهائي, the phrase naturally means final exam.

This is a nominal sentence in Arabic.

A simple way to understand it is:

• هذا = the subject/topic
• اختبار نهائي = the predicate/comment

So the sentence is structured like:

• This
  • a final exam

That is how Arabic expresses This is a final exam.

More traditionally in grammar terms:

• هذا is the mubtadaʾ or a subject-like starting element
• اختبار نهائي is the khabar or predicate

Not by itself in the same way.

هذا اختبار نهائي is understood as a complete sentence:

• This is a final exam.

If you want this final exam as a noun phrase, Arabic would normally say:

• هذا الاختبار النهائي

That phrase means:

• this final exam

So the presence or absence of الـ matters a lot here.

This is a very common beginner question.

When هذا is part of a full sentence like:

• هذا اختبار نهائي

it is functioning as this in This is a final exam.
The noun after it is the predicate, so it can stay indefinite.

But when هذا directly modifies a noun phrase, the noun is definite:

• هذا الاختبار النهائي = this final exam

So compare:

• هذا اختبار نهائي = This is a final exam.
• هذا الاختبار النهائي = This final exam.

That difference is very important.

Yes, in fully vocalized formal Arabic there would be nominative endings, because this is a nominal sentence and the predicate is nominative.

A fully inflected version would be:

هٰذا اختِبارٌ نِهائيٌّ

That would be read approximately as:

hādhā ikhtibārun nihāʾiyyun

However, in ordinary written Arabic, these endings are usually not written, and in pause they are often not pronounced.

So learners very often encounter it simply as:

هذا اختبار نهائي

and pronounce it more simply as:

hādhā ikhtibār nihāʾī

The demonstrative would change to the feminine form.

For example, with a feminine noun you would use:

• هذه = this (feminine)

So if the noun were feminine singular, the sentence would begin with هذه instead of هذا.

Also, the adjective would need to match the feminine noun as well.

For example:

• هذه مدرسة كبيرة = This is a big school.

Here:

• هذه matches the feminine noun
• كبيرة is the feminine form of the adjective

But in your sentence, اختبار is masculine, so:

• هذا اختبار نهائي

is correct.