Why did I have to change word to item?

In a for loop the word you specify after the for keyword is the name of a variable that will exist within the loop and contain the individual items of the loop. And the word you write after the in keyword is the name of the list you are pulling items from.

So if you have a for loop like you had in your example then during the first loop Python would pull out the first item of the items variable and then assign it to the word variable. Then it would run the code. Then it would pull out the second item from the items variable and store it in the word variable and run the code again. It continues doing that until it has gone though all of the items in the items variable.

That's why you had to use print(word) to print the current item. You could have completed the task without changing word to item, but then you have to use the word variable in your if check too like this:

for word in items:
    if word == 'STOP':
        break 
    print(word)