Die dokument is geheel nuut.

Yes. Die here is the definite article, so it works like English the.

A useful difference is that Afrikaans uses die for:

• singular nouns: die dokument = the document
• plural nouns: die dokumente = the documents

Unlike English, Afrikaans does not change the article for number in this case.

Because nuut comes after is and is being used predicatively.

In Afrikaans:

• after a linking verb like is, adjectives usually stay in their basic form: Die dokument is nuut
• before a noun, adjectives often take -e: die nuwe dokument

So:

• die nuwe dokument = the new document
• die dokument is nuut = the document is new

Here geheel is functioning as an adverb, modifying nuut.

So it means something like:

• entirely new
• completely new
• wholly new

Even though geheel can also appear in other roles in Afrikaans, in this sentence it is best understood as an adverb describing the degree of nuut.

Because in Afrikaans, a degree word or adverb usually comes before the adjective it modifies.

So:

• geheel nuut = entirely new
• baie nuut = very new
  although this exact phrase is less natural in many contexts

This is similar to English word order:

• completely new
• not new completely

It is understandable and grammatical, but many speakers might more often say:

• Die dokument is heeltemal nuut
• Die dokument is splinternuut

The sentence with geheel nuut has a slightly formal or careful feel. So it is not wrong, but it may sound more formal than everyday speech.

This is the normal word order for a simple Afrikaans statement:

subject + verb + complement

So:

• Die dokument = subject
• is = verb
• geheel nuut = complement

This is very similar to English:

• The document is entirely new

Afrikaans main clauses usually place the finite verb early in the sentence, and in a basic statement like this it comes right after the subject.

Afrikaans does not use grammatical gender the way languages like German or Dutch do.

So dokument is simply a noun, and you use die with it:

• die dokument

You do not have to memorize a separate masculine or feminine article for nouns in Afrikaans.

In Afrikaans, die is pronounced roughly like dee, not like the English verb die.

So:

• die ≈ dee

That is a very common point of confusion for English speakers.

Yes, in some contexts heel can also mean completely or very, and many learners will encounter it.

However, the nuance can vary depending on context. If you want a clearer, more standard equivalent of entirely/completely new, heeltemal nuut is often the safest everyday choice.

So these are possible:

• Die dokument is geheel nuut
• Die dokument is heeltemal nuut
• Die dokument is splinternuut

They are close in meaning, but differ a little in style and emphasis.