Dis nie dat e-boeke verander nie—dis net dat boekkeuses verander.

Dis is the contracted form of Dit is, meaning it is.

So:

• Dis nie dat ... nie = It’s not that ...
• dis net dat ... = it’s just that ...

This contraction is extremely common in Afrikaans, much like it’s in English.

Afrikaans usually uses double negation.

In this sentence:

• Dis nie dat e-boeke verander nie

the first nie introduces the negation, and the second nie closes it.

A natural English equivalent is:

• It’s not that e-books are changing

So the pattern is very typical Afrikaans:

• Hy werk nie vandag nie. = He isn’t working today.
• Dis nie maklik nie. = It isn’t easy.

Dat means that and introduces a subordinate clause.

So:

• Dis nie dat e-boeke verander nie literally = It is not that e-books change/are changing
• dis net dat boekkeuses verander = it is just that book choices are changing

This dis nie dat ... dis net dat ... structure is a very common way to contrast two explanations:

• It’s not that X; it’s just that Y.

Because Afrikaans verbs do not change form according to the subject in the present tense.

So all of these use the same verb form:

• ek verander
• jy verander
• e-boeke verander
• boekkeuses verander

Unlike English, Afrikaans does not add -s for he/she/it in the present tense.

After dat, Afrikaans uses subordinate-clause word order, and the verb typically comes later, often at the end.

So:

• main clause: E-boeke verander
• subordinate clause: dat e-boeke verander

In this sentence, the clause is short, so it may not look very different from English. But the rule becomes clearer in longer examples:

• Ek weet dat e-boeke vinnig verander.
• Sy sê dat boekkeuses oor tyd verander.

That final position of the verb is normal after dat.

Here net means just.

So:

• dis net dat ... = it’s just that ...

It softens the correction or clarification. The speaker is saying:

• Not this explanation
• Just this one instead

It is a very natural conversational word in Afrikaans.

Afrikaans often uses a hyphen with items like e-, letters, abbreviations, and similar elements attached to nouns.

So:

• e-boek = e-book
• e-boeke = e-books

The hyphen makes the form clear and easy to read. This is standard Afrikaans spelling.

Afrikaans loves compound nouns and usually writes them as one word.

So:

• boek = book
• keuse = choice
• boekkeuse = book choice
• boekkeuses = book choices

This is very normal in Afrikaans. Where English often uses two words, Afrikaans often combines them into one.

Boekkeuses literally means book choices or choices of books.

Depending on context, it could suggest:

• the books people choose
• reading preferences
• the selection of books available
• which kinds of books are being picked

So the sentence contrasts:

• e-books themselves are not changing with
• the choices people make about books are changing

Yes, it is a very common Afrikaans pattern.

It works like English:

• It’s not that ..., it’s just that ...

It is used when you want to reject one interpretation and give the real reason instead.

For example:

• Dis nie dat hy kwaad is nie—dis net dat hy moeg is.
  • It’s not that he’s angry—it’s just that he’s tired.

So the sentence you were given follows a very natural everyday structure.

The dash marks a strong contrast between the two parts:

• not this
• but rather this

So it helps the sentence feel more emphatic and clear.

A comma could also appear in some contexts, but the dash is very effective here because the sentence is making a correction or contrast. It sounds a bit like a pause in speech:

• It’s not that e-books are changing — it’s just that book choices are changing.