هذا الجواب صحيح.

Arabic often uses a nominal sentence in the present tense, with no written or spoken verb equivalent to English is/are.

So:

• هذا الجواب صحيح
• literally: this answer correct
• natural English: This answer is correct

In the present tense, Arabic usually leaves out is.
If you wanted a past-tense version, you would use a verb, for example:

• كان هذا الجواب صحيحًا = This answer was correct

هذا is a demonstrative pronoun, meaning this.

In this sentence, it points to الجواب:

• هذا = this
• الجواب = the answer

Together, هذا الجواب means this answer.

A useful pattern is:

• هذا الكتاب = this book
• هذا الرجل = this man
• هذا الجواب = this answer

Because الجواب is a masculine singular noun.

In Arabic, demonstratives must match the noun in gender and number:

• هذا = this (masculine singular)
• هذه = this (feminine singular)

So:

• هذا الجواب = this answer
• but هذه الإجابة = this answer

Both جواب and إجابة can mean answer, but جواب is masculine and إجابة is feminine, so the demonstrative changes.

الـ is the Arabic definite article, equivalent to the.

So:

• جواب = an answer / answer
• الجواب = the answer

After a demonstrative like هذا, Arabic normally uses a definite noun:

• هذا الجواب = this answer

That is the normal pattern in Standard Arabic.

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

So:

• جواب صحيح = a correct answer
• الجواب الصحيح = the correct answer

However, in your sentence, صحيح is not just an adjective inside a noun phrase. It is functioning as the predicate of the sentence:

• هذا الجواب = the subject/topic
• صحيح = correct

So the whole sentence means:

• This answer is correct

Arabic naturally puts the predicate after the subject here.

This is a very common learner question.

In هذا الجواب صحيح, صحيح is the predicate of the sentence, not part of the noun phrase this answer. Predicates in this kind of sentence are often indefinite, so you get:

• هذا الجواب صحيح = This answer is correct

But compare that with:

• هذا الجواب الصحيح = this correct answer

In that version, الصحيح is an adjective directly modifying الجواب, so it must match it in definiteness.

So:

• الجواب صحيح = the answer is correct
• الجواب الصحيح = the correct answer

Yes.

Arabic has a lot of agreement. Here are the key points:

1. هذا matches الجواب in being masculine singular.
2. صحيح also matches الجواب in being masculine singular.

So the sentence is internally consistent:

• هذا → masculine singular
• الجواب → masculine singular
• صحيح → masculine singular

If the noun were feminine, you would change the other words too where needed. For example:

• هذه الإجابة صحيحة = This answer is correct

Notice:

• هذه instead of هذا
• صحيحة instead of صحيح

In fully vocalized Standard Arabic, you would usually see:

• هٰذَا الْجَوَابُ صَحِيحٌ

More grammatically explicit:

• هٰذَا = hādhā
• الْجَوَابُ = al-jawābu
• صَحِيحٌ = ṣaḥīḥun

Why those endings?

• الجوابُ is the subject/topic of the nominal sentence, so it is nominative
• صحيحٌ is the predicate, so it is also nominative

In normal everyday writing, these short vowel endings are usually not written, so you commonly just see:

• هذا الجواب صحيح

A careful MSA pronunciation would be approximately:

• hādhā al-jawābu ṣaḥīḥ

Or with full case ending on the last word:

• hādhā al-jawābu ṣaḥīḥun

A few pronunciation notes:

• هٰذا: dh is like the th in this
• جواب: the ā is long, so ja-wāb
• صحيح:
  • ṣ is an emphatic s
  • ḥ is a stronger, breathier h from the throat
  • ī is long

A rough learner-friendly version is:

• HAA-thaa al-ja-WAAB sa-HEEH

But that does not fully capture the Arabic sounds ṣ and ḥ.

Yes. That is also correct Arabic and means essentially the same thing:

• هذه الإجابة صحيحة = This answer is correct

The main difference is vocabulary and grammatical gender:

• جواب = answer, reply (masculine)
• إجابة = answer, response (feminine)

So:

• هذا الجواب صحيح
• هذه الإجابة صحيحة

Both are good MSA sentences.

Both can mean answer, but they are not always used in exactly the same way.

A simple learner-friendly distinction is:

• جواب often means answer/reply
• إجابة often means answer, especially in contexts like an answer to a question, a test answer, or a response

In many contexts, they overlap a lot, and both can be natural. In your sentence, الجواب sounds completely normal.

The normal, straightforward order is:

• هذا الجواب صحيح

That is the most neutral way to say This answer is correct.

You may also encounter slightly different structures, but they can change the nuance:

• هذا جواب صحيح = This is a correct answer
  (not necessarily the answer, just a correct one)

• الجواب صحيح = The answer is correct

So the exact wording affects definiteness and emphasis. For the meaning This answer is correct, your original sentence is the standard choice.