The message indicates the line and column in the block where the invalidity originates.
Because ORA-06550 errors are related to PL/SQL, they're typically (always?) followed by a PLS-xxxxx error message.
Simple example
The following block has a type which makes it impossible for Oracle to execute:
declare
txt varchar2(20);
begin
txt := 'Hello world.';
dmbs_output.put_line(txt);
-- ^^
-- || Note the typo!
end;
/
Trying to execute the block results in the error message
ERROR at line 5:
ORA-06550: line 5, column 4:
PLS-00201: identifier 'DMBS_OUTPUT.PUT_LINE' must be declared
ORA-06550: line 5, column 4:
PL/SQL: Statement ignored
The identifier which is found at line 5, column 4, is the erroneus dmbs_output.