I've got this statement in Java:
It's a bitwise OR operation. It's modifying things at a binary level.
011 3 in binary: | 100 in decimal: | 4 ___ ___ 111 7
Open Windows calc using scientific mode. You can flip between decimal and binary (and hex) and perform bitwise operations including or, and, xor, etc.
To do a bitwise or in your head or on paper, compare each digit of the same ordinal. If either number is a 1, the result at that ordinal will be 1.