To find a mean, you have to add all of the numbers together, then divide by the number of numbers there are.
19 + 15 + 5 + 19 + 19 + 17 = 94
94/6 = 15.67
The mean is 15.67
To find the median put all the numbers in order, then find the middle number.
5, 15, 17, 19, 19, 19
Since 18 is between 17 and 19, the median is 18. :)
Hopefully this helps! If you have any more questions or don't understand, feel free to DM me, and I'll get back to you ASAP! :)