[Solved]-Why doesn't dataGrouping.units work here?-Highcharts

Data grouping is a feature exclusive to Highstock.

First, you need to import Highstock instead of Highcharts:

import Highcharts from 'highcharts/highstock';

and second, define constructorType for the component:

    <HighchartsReact
      ...
      constructorType="stockChart"
    />

Docs: https://www.highcharts.com/docs/stock/data-grouping