'n is the Afrikaans indefinite article, so it means a or an.
In this sentence:
A few useful things to know about 'n:
So 'n indruk is the normal way to say an impression.
The apostrophe is just part of the normal spelling of the Afrikaans indefinite article.
So 'n is not a contraction you need to analyze each time; it is simply the standard written form for a/an in Afrikaans.
Learners often notice that it looks unusual, but it is extremely common and completely normal.
Because maak 'n indruk is a standard expression meaning to make an impression.
It is very close to English:
You can think of it as a set phrase. If you want to say who is impressed, you can add op:
It can be both.
Sometimes maak is literally make/do, but in many expressions it is part of an idiomatic phrase. Here, maak 'n indruk is one of those common combinations.
So it is best to learn:
That will sound much more natural than translating word by word every time.