[Solved]What does Matlab Boxplot do?

If you don't understand what the "error bars" the Matlab Boxplot does, you should read this.

Short answer:
Red line in the middle = median
Box edge = First and third Quantile
Whister ends = The default value for 'Whisker' corresponds to approximately +/–2.7σ and 99.3 percent coverage if the data are normally distributed


For more please read :
https://www.mathworks.com/help/stats/boxplot.html
and
http://www.purplemath.com/modules/boxwhisk.htm