Because the sentence begins with the indien clause. In Afrikaans main clauses, the finite verb normally stays in the second position.
So the first slot is already taken by the opening clause:
That means the main clause comes next with the verb first:
This is called inversion.
Compare:
So after the fronted if-clause, the verb comes before the subject.
Reiskoste means travel costs or travel expenses.
It is a compound noun:
Afrikaans forms compound nouns very often, just like Dutch and German.
Other examples:
In meaning, it refers to expenses or costs, so it is plural in idea, but Afrikaans often treats such compound nouns as a single noun form.
So you can think of reiskoste as a set or category of costs: travel expenses.
English does something similar with words like luggage or equipment, where the grammar and the meaning do not always line up neatly with a simple singular/plural pattern.
Afrikaans sometimes leaves that implicit when the meaning is clear from context.
So motiveer sy reiskoste can be understood as she justifies (her) travel expenses.
If you wanted to make it more explicit, Afrikaans could use haar:
But in many official or bureaucratic contexts, the shorter version is common if the meaning is obvious.
Not always. Sy can be tricky because it can mean different things depending on context.
It can mean:
But in this sentence:
You can tell from the grammar:
It does not mean his here.
Yes, it is standard to use a comma after the opening subordinate clause.
So:
The comma helps separate:
This is very common in Afrikaans.
A very useful pattern is:
Using this sentence:
So the main lessons are: