A new-to-programming student asked me why you would use functions. I gave this example and I feel like this explains it well, building up abstraction from a concrete example to a more powerful, general one. For the record, you shouldn't use '+' to put strings together and you shouldn't do language translation this way. This is just to illustrate…

why_you_need_functions.py

def say_hello_glen():
    return 'hello, glen'

def say_hello(name):
    return 'hello, ' + name

def greet(name, language):
    if language is 'spanish':
        return 'hola, ' + name
    if language is 'english':
        return 'hello, ' + name
    else:
        return 'heeeey'