I assume you had an ORA-01858 error because it looks like you're comparing a string which isn't in date format with a date field.
Assuming BAA_MONTH is a date field, use this: where to_char(BAA_MONTH, 'Mon-YY') = 'Jan-14'
By the way, it's a good idea to use 4 characters for the year.
Alternatively, you may find this is more efficient for your query:
where BAA_MONTH between to_date('01-jan-2014', 'dd-mon-yyyy') and last_day (to_date('01-jan-2014', 'dd-mon-yyyy'))