Below mention of sql*plus query in this what is meaning of sign ( ) and " "

Question

why using this signs in to query of sql*plus eg.
select ename, sal, round(sal*2/365) "dailysal" from emp;

Answer 1

where is sign used in your example. also try to explain the problem properly

Answer 2

. * " ， ； _ ' what is an interpretation of this all signs? how we know when nd where to required this signs?