What is NomalProfit of Calculation of Category importance ??

hi,everyone.

please answer me my quension.

my question is 'What is NomalProfit of Claclulation of Category importance??'

i have seen help,but only read

"The fact that the distribution of the target for this category is significantly skewed towards high values or low values

when compared with the distribution of the target on the entire population "

i have not know this text meaing.

pleas tell me this text meaning clearly and easily.

thanks.