First completion

Ah, return in Python is used for functions.
Normally when you pass a variable in a function like so:

def add_one(num):
    result = num + 1
    return result

number = 5
result = add_one(number)
print(result)  # this will print "6" in the console

With this you can make code cleaner and more easily re-usable.
Lets say you want to do a complex mathematical computation but you don't want to write it down multiple times, here a function can help.

This:

one = 32 * 48 - 48 + 32
two = 4121 * 958 - 958 + 4121
print(one * two - two + one)  # this will print "6120767604" in the console

Would become this:

def complex_function(a, b):
    return a * b - b + a

one = complex_function(32, 48)
two = complex_function(4121, 958)
print(complex_function(one, two))  # this will print "6120767604" in the console

Notice that the outcome is still the same, but now when the mathematical equations changes you only have to change it once instead of 3 (or potentially more times).