You can transform your data using many functions such as square root, logarithm, power, reciprocal or arcsine.
Minitab determines an optimal power transformation. The Box-Cox transformation is easy to understand, but is limited and often does not determine a suitable transformation. It is also only available for data that are positive.
If the Box-Cox algorithm does not determine a suitable transformation, then try the Johnson transformation. The Johnson transformation function is more complicated, but is very powerful for determining an appropriate transformation.