random

the challenge is asking the following:
# EXAMPLE
# random_item("Treehouse")
# The randomly selected number is 4.
# The return value would be "h"

so you have a string "Treehouse"  which nothing more than an iterable of chars.  To prove thsi:

for letter in "Treehouse":
    print(letter)

will produce 
T
r
e
e
h
o
u
s
e

the length of the string is len("Treehouse")
print(len("Treehouse")) should result in 9

so now the challenge is asking you to create a function named  random_item which you are going to pass a string as a param

def random_item(string):


in this function you want to grab a random number between 1 and the length of the length of the string

this should do it
print(random.randint(1,len(string)))


therefore, so far we have

def random_item(string):
   a_random = random.randint(1,len(string))


we now just need to return the letter at position a_random 

this would be return string[a_random]

so now now we have a full function

def random_item(string):
   a_random = random.randint(1,len(string))
   return string[a_random]

and to call it, I would do this 

a_letter = random_item("TennesseeVolsAreGreat")
print(a_letter) 

There you got it.

I hope that by walking you through the thought process, this will help you break down a larger problem into smaller logical steps through which you can solve much original problem.

please tweak the example I provided so meet the challenge requirements.   For example, the challenge is expecting you to print from inside the function.

good luck