What means " & " in python, what action it does?

Answer 1

& represents a bitwise AND operator. It returns True only if both arguments are 1.
0 & 0 = False
0 & 1 = False
1 & 0 = False
1 & 1 = True

Answer 2

& in Python is a set operation used for intersection if two sets.

Answer 3

& is a bitwise operator

https://wiki.python.org/moin/BitwiseOperators