Ons gaan die salarisstrokie na, ongeag of hulle haar onderbetaal.

Because the verb here is nagaan, which is a separable verb in Afrikaans.

• Full verb: nagaan = to check, examine, review
• In a main clause, the first part stays in the normal verb position, and the particle moves to the end:
  • Ons gaan die salarisstrokie na.

So this is not the preposition na meaning after or to. It is the second part of the verb nagaan.

No. In this sentence, gaan ... na belongs together as nagaan.

So:

• Ons gaan die salarisstrokie na = We check / review the payslip
• not We are going to the payslip

This can be confusing because gaan often does mean go or helps form a future meaning. But the na at the end shows that this is the separable verb nagaan.

Salarisstrokie is a compound noun:

• salaris = salary
• strokie = little slip / slip

Together, salarisstrokie means payslip.

Afrikaans, like Dutch and German, often joins nouns into one word. So where English uses pay slip or payslip, Afrikaans commonly writes one compound: salarisstrokie.

Also, strokie has a diminutive ending -ie, but in words like this it is often just the normal everyday term, not necessarily something literally small or cute.

Ongeag of means regardless of whether.

So:

• ongeag = regardless
• of = whether / if

In this sentence:

• ongeag of hulle haar onderbetaal = regardless of whether they underpay her

It introduces a condition that does not change what the main clause is saying.

Here of means whether.

After ongeag, Afrikaans often uses of to introduce the idea of whether something is true or not.

So:

• ongeag of hulle haar onderbetaal = regardless of whether they underpay her

In English, if and whether can sometimes overlap, but here whether is the better match.

Because of introduces a subordinate clause, and in Afrikaans subordinate clauses the verb usually goes to the end.

So the structure is:

• hulle = they
• haar = her
• onderbetaal = underpay

That gives:

• of hulle haar onderbetaal

This is a normal Afrikaans subordinate-clause pattern:

• conjunction
• subject
• object
• verb at the end

Because they behave differently.

• nagaan is a separable verb
• onderbetaal is treated as an inseparable verb

So:

• Main clause: Ons gaan die salarisstrokie na
• Subordinate clause: ... of hulle haar onderbetaal

You do not split onderbetaal into something like betaal ... onder. It stays together as one word.

This is a very common thing learners need to get used to: some Afrikaans verbs with prefixes split, and some do not.

Because they have different jobs in the clause.

• hulle = they → the subject, the people doing the action
• haar = her → the object, the person receiving the action

So:

• hulle haar onderbetaal = they underpay her

A native English speaker may find this straightforward in meaning, but it is useful to notice that Afrikaans does not change word order here in a strange way; it is still subject + object + verb at the end because of the subordinate clause.

The sentence is in the present tense.

• Ons gaan die salarisstrokie na = We check / are checking / review the payslip
• hulle haar onderbetaal = they underpay / are underpaying her

As often happens in Afrikaans, the exact English tense you choose depends on context. The Afrikaans form itself is simpler and often covers what English expresses with either simple present or present continuous.

The comma separates the main clause from the following added clause.

Main clause:

• Ons gaan die salarisstrokie na

Added subordinate idea:

• ongeag of hulle haar onderbetaal

So the comma helps show the boundary between the two parts and makes the sentence easier to read. This is very normal in Afrikaans punctuation when a clause like this is added after the main statement.