select col1, col2
into name1, name2
from table1
where col1=col;
m_sub := 'Subject ';
m_msg := 'Hello '||name||' ,'||/n||/n||'Your order has been placed.';
Error(34,33): PLS-00103: Encountered the symbol "/" when expecting one of the following: ( - + case mod new null avg count current max min prior sql stddev sum variance execute forall merge time timestamp interval date pipe
Chr(Number) should work for you.
select 'Hello' || chr(10) ||' world' from dual
Remember different platforms expect different new line characters: