Answer:
your code looks correct. I think your issue is just indentation. with Python you want to be very careful with spacing.
Step-by-step explanation:
c = 0
while (True):
user_input = input("Please enter the next word: " )
if user_input == "STOP":
break
c += 1
print ("# {}: You entered {}".format(c, user_input))
print("All done. {} words entered.". format(c))