Once a member receives a review, they will be notified via email that a review has been submitted for their listing. The member is then able to login to their member account and choose whether to approve the review or decline it. 

This allows members who are signed up on your site to effectively manage their online reputation.

Alternatively, you can approve these reviews as the administrator of the site.

You can go to Members -  Member Reviews in the side navigation menu in the Admin area of your site. Here you will see a list of all of the reviews that have been received by your members and you can choose to approve or decline them from there.