The Benevolence theme comes with one page template to display Galleries.
Setting Up a Galleries Page
To display a grid of galleries, first create a new page by selecting Pages → Add New from the main menu. You can name this page whatever you like, give it a header image, etc.
Importantly, select Galleries Grid from the Template section of the Page Attributes box. Save the page. Your galleries will now be displayed on that page.
Add the page to a menu using Appearance → Menus, or link to it from elsewhere on your site, to make your galleries page accessible to users.