What does this symbol mean '&'?

The symbol & in programming languages like C and C++ is primarily used as the bitwise AND operator.

• Bitwise AND compares each bit of two numbers and returns a new number with bits set to 1 only if both bits were 1.
• For example: 5 & 3 results in 1 because:

 5 = 1013 = 011& = 001 → 1

Note: In C/C++, the & symbol is also used as the "address-of" operator in certain contexts, but unless specified otherwise, the standard meaning is bitwise AND.