Yes, in Die antwoord is nul, antwoord is a noun: answer.
Afrikaans can also use antwoord as a verb, meaning to answer, depending on the context.
For example:
In your sentence, it is clearly a noun because it comes after die.
Because Afrikaans and English are related Germanic languages, some common words look the same.
In Afrikaans, is is the present-tense form of to be, just like English is.
A useful thing to know is that Afrikaans verbs usually do not change much by person:
So is stays the same much more than in English.
Because nul is being used as a predicate after the linking verb is.
In a sentence like this, Afrikaans normally does not add an article before a number:
This is similar to English:
In a simple yes/no question, Afrikaans usually puts the verb first:
That literally matches the English pattern:
So the statement:
becomes the question:
Afrikaans usually uses a double nie in negative sentences.
So: Die antwoord is nie nul nie.
This means: The answer is not zero.
A very common pattern is: subject + verb + nie + rest + nie
That double negative structure is one of the most important features of Afrikaans grammar.
A rough English-friendly pronunciation is:
dee AHNT-foort is nuhl
A few useful notes:
If you want to sound more natural, keep the sentence fairly even and straightforward: Die antwoord is nul.
It is capitalized only because it begins the sentence.
If the same phrase appeared in the middle of a sentence, it would normally be lowercase:
So die is not capitalized because it is special grammar; it is just normal sentence-initial capitalization.