Yes. The singular is appel and the plural is appels.
Many Afrikaans nouns form the plural with -e or -s, depending on the word. In this case, appel becomes appels.
Also, after a number greater than one, Afrikaans uses the plural noun, just like English:
Because you do not normally use an article with a bare number phrase like this.
If you wanted the four apples, you would say:
If you wanted an apple, you would say:
So in Ek het vier appels, the sentence simply means I have four apples, with no extra article needed.
Ek het nie vier appels nie.
Afrikaans usually uses a double negation pattern:
So:
This is a very important Afrikaans pattern.
For a yes/no question, Afrikaans usually puts the verb first:
Het ek vier appels?
That means Do I have four apples?
So compare:
This verb-first pattern is very common in Afrikaans questions.
It is capitalized only because it is the first word of the sentence.
Afrikaans does not capitalize the word for I in the middle of a sentence the way English does.
So:
That is a common thing for English speakers to notice.