Most words are made plural in Afrikaans by adding an e.
So, boek 'book' becomes boeke 'books' or hond 'dog' becomes honde 'dogs'.
Of course, it isn't quite as simple as this as (and there are rules) a word like kop 'head' becomes koppe in the plural, but it is easier to listen and pay attention than try and remember that you double a consonant before a short vowel (or whatever).
Quite a few common nouns add an s in the plural instead of e.
Many of these are loan words coming from English rather than dutch. Regardless you just have to learn when a word is made plural with e or s.
Here are a few examples of words made plural by adding an s.
And some plurals are irregular.
These exceptions (e.g. plurals which do not end in an e or s in the plural) just have to be learnt, or acquired through exposure to the language.
Learning Afrikaans vocabulary has some suggestions to help with vocabulary acquisition. One useful tip is to active learning. Think about what you are doing and don't just repeat words endlessly. Maybe look for patterns. For example a few of these plurals end with g in the singular.
This lesson has some of the more common irregular plurals.Start