Die kandidaat heg die CV en dekbrief voor die sperdatum aan.

Because the full verb is aanheg, which is a separable verb in Afrikaans.

In a normal main clause:

• the finite verb goes to the second position: heg
• the separable part goes to the end: aan

So:

• Die kandidaat heg die CV en dekbrief voor die sperdatum aan.

But in an infinitive or after a modal verb, it stays together:

• Die kandidaat moet die CV en dekbrief voor die sperdatum aanheg.

This is very similar to separable verbs in Dutch and German.

Yes. They are two forms of the same verb.

• aanheg = dictionary / infinitive form
• heg ... aan = the split form used in a main clause

So you should think of the verb as aanheg, but remember that Afrikaans often splits it when it is conjugated in a main clause.

Die is the definite article, so it usually means the.

A very useful thing for English speakers: Afrikaans uses die for:

• singular nouns
• plural nouns
• all grammatical genders

So unlike languages such as German, you do not have to learn different forms for masculine, feminine, or neuter nouns.

In this sentence:

• die kandidaat = the candidate
• die CV en dekbrief = the CV and cover letter

Because one article can cover both nouns when they are joined by en.

So:

• die CV en dekbrief = the CV and cover letter

This is natural Afrikaans.

You can also repeat the article if you want to emphasize each item separately:

• die CV en die dekbrief

But in ordinary usage, the single die is completely normal.

This sentence follows the usual main-clause word order in Afrikaans:

1. Subject: Die kandidaat
2. Finite verb: heg
3. Object: die CV en dekbrief
4. Time phrase: voor die sperdatum
5. Separable particle: aan

So the structure is roughly:

• Subject + finite verb + rest + particle

Afrikaans is a verb-second language in main clauses, which means the finite verb usually comes second.

Yes. Time expressions are fairly movable in Afrikaans.

For example, you can also say:

• Voor die sperdatum heg die kandidaat die CV en dekbrief aan.

That still means the same thing, but now the time phrase is being given more emphasis.

Because Afrikaans is verb-second, if voor die sperdatum comes first, the finite verb heg must still come second.

Not always. Voor can mean different things depending on context.

Common meanings include:

• before in time
• in front of in space

In this sentence, it clearly means before, because die sperdatum is a time-related noun.

So:

• voor die sperdatum = before the deadline

Sperdatum is a compound noun, which is very common in Afrikaans.

It is made up of:

• sper = block / close / cut-off
• datum = date

Together, sperdatum means deadline or closing date.

Afrikaans usually writes compound nouns as one word, so this is completely normal. The same thing happens with:

• dekbrief = cover letter

For English speakers, this is worth getting used to, because English often writes these as two words, while Afrikaans often joins them.

Afrikaans normally uses double negation.

So the negative version is:

• Die kandidaat heg nie die CV en dekbrief voor die sperdatum aan nie.

You can think of it like this:

• first nie appears after the finite verb area
• second nie appears near the end of the clause

This double nie ... nie pattern is one of the most important features of Afrikaans grammar.

Yes, CV is very commonly used in Afrikaans.

You may also see:

• curriculum vitae
• sometimes résumé, depending on context

But CV is perfectly normal and widely understood.

So in this sentence, die CV sounds natural.

Yes, but the meaning changes slightly.

• heg ... aan / aanheg = attach
• stuur = send

So:

• Die kandidaat heg die CV en dekbrief aan.
  = The candidate attaches the CV and cover letter.

• Die kandidaat stuur die CV en dekbrief.
  = The candidate sends the CV and cover letter.

If you are talking about adding files to an email or application, heg ... aan is the more precise verb.