What's the meaning of this operator "~"

Question

Example for description please

Answer 1

~n = -n - 1

~9 = -9 - 1 = -10
~-4 = -(-4) - 1 = 3

Answer 2

It is the bitwise operator,

Here provide the details,
https://wiki.python.org/moin/BitwiseOperators
https://realpython.com/python-operators-expressions/