What does [ ] mean as an output in Python?

I am trying to write code to count the number of upper case letters in a string using Python. I have written the following but instead of the code returning the number of Upper Case letters it returns []? An help would be gratefully recieved.

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import re

while True:
    strPassword = input("Please enter your password: ")
    length = len(strPassword)
    if length < 6 or length > 12:
        print ("It is not the correct length")
    else:
        break
print ("Password OK")

upper = 0
lower = 0
number = 0

print (re.findall("A-Z", strPassword, 0))

import re</p><br /><p>while True:<br /><br /> strPassword = input(“Please enter your password: “)<br /><br /> length = len(strPassword)<br /><br /> if length < 6 or length > 12:<br /><br /> print (“It is not the correct length”)<br /><br /> else:<br /><br /> break<br /><br />print (“Password OK”)</p><br /><p>upper = 0<br /><br />lower = 0<br /><br />number = 0</p><br /><p>print (re.findall(“A-Z”, strPassword, 0))

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