When an employee requests an absence from the office (vacation, personal day, sickness), a message will be displayed on the employer dashboard letting you know that there are 'absences requiring your approval.' Click on the individual employee listed to go through to the absences section. As the employer, you can choose to approve or decline the request.
The employee will be notified by email once approved or declined. The comments box allows the employer to provide a reason for the decline and this will be noted in the decline email sent.