I need a bit of help with an assignment. Given statistics of 2 variables (#of cigarettes smoked vs a having a chronic condition (Yes/No)), do Box Plots and Measures of Spread (Standard Deviation, Mean Deviation and Variance) mean anything with the data?

I want to make sure of something though. Are Box Plots and Measures of Spread meant for One Variable Statistics or can they be used for Two Variable Statistics as well?

Thanks in advance for any help.