Function to count words in a list up to and including Sam

[Oldman45]

Good Morning
I am running Python 3.8.5 and trying to develop a function that counts the number of words in a list up to and including the word Sam. Here is what I have developed so far:

lst = ["able", "been", "state", "Sam", "beer"]
length = len(lst)
def test(lst):
    length = len(lst)
for w in lst:
    if w == "Sam":
        break
    print(w)
print(test(lst))

The out put I get is:
able
been
state
None

I would appreciate input to:
1. Help me understand why I cannot get the answer as a number (4)
2. Understand why I have to state 'length = len(lst) as a variable outside of the function, then repeat it as the first line of the function

Thanks in advance