'n is the Afrikaans indefinite article, equivalent to English a or an.
So 'n dag means a day.
A couple of useful notes:
Because Afrikaans places gelede after the time expression.
So:
This is different from English, where ago also comes after the time phrase, but learners sometimes expect the structure to behave differently when the whole sentence gets longer. In Afrikaans, gelede stays attached to the time phrase.
Af means off here, and it is part of the idea af wees, meaning to be off.
Afrikaans often puts the finite verb early in the sentence, and other parts of the predicate later. So:
A very literal word-for-word order would look something like:
That is not natural English, but it helps show the Afrikaans structure.
No, af is not the main verb by itself.
The main verb is was, the past tense of wees, meaning to be.
Af works like off in English in a sentence like The power was off.
So the important combination is:
No. Afrikaans often allows some flexibility, especially with time expressions.
A very natural alternative is:
That also means the same thing. The key point is that gelede stays with 'n dag.
So you can think of 'n dag gelede as one time phrase that can move around as a unit more easily than gelede by itself.
Yes, it is understandable and grammatical.
That said, many speakers might more naturally say:
This is often a little more natural because the time phrase comes first. But the original sentence is still a good example of Afrikaans word order and is perfectly useful for learning.