Nie net my buurman nie, maar ook sy dogter help in die tuin agter die heining.

It means not only ... but also ...

So this sentence is built to highlight two people:

• Nie net my buurman nie = not only my neighbour
• maar ook sy dogter = but also his daughter

It is a very common Afrikaans pattern for adding emphasis.

This is part of Afrikaans negative structure. Afrikaans often uses a kind of double negation, and in this expression the pattern is fixed:

• nie net X nie, maar ook Y

The first nie starts the negative idea, and the second nie closes that first part. So you should learn nie net ... nie as a set pattern.

The comma helps separate the two balanced parts of the sentence:

• Nie net my buurman nie
• maar ook sy dogter

This is similar to how English often separates contrasting or paired elements in longer sentences. In Afrikaans, the comma here is normal and helpful.

Yes. Buurman literally means male neighbour or neighbouring man.

Related words:

• buurman = male neighbour
• buurvrou = female neighbour

So in this sentence, the speaker is specifically referring to a man.

These are possessive words placed before the noun:

• my buurman = my neighbour
• sy dogter = his daughter

Afrikaans uses these possessive determiners much like English:

• my = my
• jou = your
• sy = his
• haar = her
• ons = our
• hulle = their

So sy dogter means his daughter.

Because Afrikaans verbs do not change in the present tense the way English verbs do.

Compare:

• Ek help = I help
• Hy help = he helps
• Sy help = she helps
• Hulle help = they help

The verb stays help for all persons. That is why the sentence uses help, even though the subject includes other people.

Because the whole subject is:

Nie net my buurman nie, maar ook sy dogter

That entire phrase functions as the subject of the sentence. After the full subject comes the verb:

• Nie net my buurman nie, maar ook sy dogter
  • help

So the structure is basically:

[Not only my neighbour, but also his daughter] help in the garden ...

Here agter means behind.

So:

• agter die heining = behind the fence

English speakers sometimes confuse behind and after, but in this sentence it is clearly a location word, not a time word.

Most naturally, it describes the garden:

• in die tuin agter die heining = in the garden behind the fence

So the image is that the garden is located behind the fence. While context can sometimes make things a little flexible, this sentence most strongly attaches agter die heining to die tuin.

Die is the Afrikaans definite article, meaning the.

So:

• die tuin = the garden
• die heining = the fence

A useful thing for learners is that Afrikaans does not make you choose different forms of the for different genders in the way some other languages do. Die is the normal definite article for these nouns.

Yes. A simpler, less emphatic version would be:

My buurman en sy dogter help in die tuin agter die heining.

That means: My neighbour and his daughter help in the garden behind the fence.

The original sentence is more emphatic because it stresses that it is not only the neighbour, but also the daughter.