For loops, strings and printing words with even characters

[volcano63]

mystring = "Secret agents are super good at staying hidden."
mystring.split()

Strings are immutable objects - meaning that they cannot be changed "in-place". You essentially create a temporary list object without assigning the result - so that list is lost

counted_string = len(mystring)
int(counted_string)

Result of len function is integer - and the second line again does nothing

for i in counted_string:    
    if i %2 == 0:
        print(i)

In Python, you iterate over lists directly; if you need index - you use enumerate function; if you want to iterate over range of values - you use range function (just to explain your mistake, don't need it here)

This video is highly recommended for those learning how to loop in Python