Comments are used to explain certain lines of code in plain English. They are not executed when the code is run.
# This is a single-line comment
"""
This is a multi-line comment
"""Note 1: Triple quotes are used to span the comment across multiple lines, to create multi-line Strings and to create docstrings.
Note 2: I think that depending on how you can compile your code, your comments can be omitted from the produced bytecode to make it more lightweight and fast.