This is the 334th most frequent Afrikaans word.
watter
"Which."
The word "watter" is used here as a question word to identify or select among options.
Watter boek wil jy lees?
Which book would you like to read?
In this sentence, "watter" is used to express uncertainty about selecting from options.
Ek weet nie watter een beter is nie.
I don't know which one is better.
Here, "watter" is used to refer to an unspecified choice among several possibilities.