It's an operator called ">&", the 1 is the parameter.

Well sure, but surely this takes some inspiration from both `&` as the "address of" operator in C as well as the `>` operator which (apart from being the greater-than operator) very much implies "into" in many circumstances.

So `>&1` is "into the file descriptor pointed to by 1", and at the time any reasonable programmer would have known that fd 1 == STDOUT.