Hi, I'm happy to help!
for a box an whisker plot, maximum and minimum values on the edge of the lines. The maximum shown here is 8, because the line ends there. The minimum is -8 because the line ends there.
The median value is shown by the middle line, which is 4.
To sum it up: Maximum: 8, Minimum: -8, Median: 4\
I hope this was helpful, keep learning! :D