The box plot shows the total amount of time, in minutes, the students of a class spend reading each day:

what information is provided by the box plot?

the mean for the data
the median for the data
the number of students who provided information
the number of students who read for more than 21.5 minutes

The information that is provided by the box plot is:

                  The median for the data.

Clearly after looking at the box and whisker plot we observe that:

The starting point of the whisker gives us the minimum value of the data i.e. '1'

The starting point of the box gives us the first or lower quartile i.e.

The middle of the box gives us the middle quartile or median i.e.

The end point of the box gives us the upper or third quartile i.e.

The end point of the whisker gives us the maximum value of the data i.e. '10'

         Hence, we obtain the median of the data.