Hi,
you have to use dynamic SQL here:

execute immediate 'Select count(*) from '||TBLNAME into ROW_CNT;

You tried po pass object name through a bind variable and that's not possible.

Remember also that tables have their owners and you need to use the owner name along the table name if you want to query tables outside your own schema.

BTW, you didn't write a package but an anonymous PL/SQL block ...