Please can anyone explain the slicing operator?

Question

I didn't understand this:
>>>S=mystring
>>>S[0:3:-1]
>>>''

Answer 1

StackOverflow has a nice thread on this topic👇
https://stackoverflow.com/questions/509211/understanding-slice-notation

Answer 2

Here is a python tutorial for slicing:
https://www.sololearn.com/learn/Python/2453/

Answer 3

Om Kumar thnx bro