I assume you're doing something like the following:
declare
v_temp varchar2(20);
begin
execute immediate 'create table temp(name varchar(20))';
execute immediate 'insert into temp values(''XYZ'')';
select name into v_name from temp;
end;
At compile time the table, TEMP, does not exist. It hasn't been created yet. As it doesn't exist you can't select from it; you therefore also have to do the SELECT dynamically. There isn't actually any need to do a SELECT in this particular situation though you can use the returning into syntax.
declare
v_temp varchar2(20)
begin
execute immediate 'create table temp(name varchar2(20))';
execute immediate 'insert into temp
values(''XYZ'')
returning name into :1'
returning into v_temp;
end;
However, needing to dynamically create tables is normally an indication of a badly designed schema. It shouldn't really be necessary.