This is the 162nd most frequent Afrikaans word.
grootste
Largest.
Here 'grootste' is used as the superlative form of the adjective 'groot' (big) to describe the largest mountain among several.
Daardie berg is die grootste van almal.
That mountain is the largest of them all.
Here 'grootste' is used metaphorically to mean the most significant or most impactful issue in this context.
Die grootste probleem wat ons het, is tydsbestuur.
The biggest problem we have is time management.
'Grootste' here modifies 'getalle' (numbers), indicating the highest quantity or amount present.