It doesn't represent slavery. Hate groups adopted this flag but it's not a hate group flag.They adopt the american flag too.   If you think it represents slavery you are stuck in the past .       
It represents the South,:
1:    Honesty
2:,    hard work,   
3:     no nonsense,  
4:     good values,  
5:     being truthful,  
6:     Southern hospitality,
 7:    military service, 
 8:    Patriotism, 
 9:    being proud of your country instead of hating it,   
10:    family values,    
11:   being kind to those less fortunate than yourself.