Title of Template suffix - page.list-collections

You do not have a link list with a handle set to title-of-template-suffix-page-list-collections, or you do and it's empty. Go ahead and create a link list called Title of Template suffix - page.list-collections on your Navigation page and populate that link list with links that point to collections, to see collections listed here. Make sure the link list also has a handle set to title-of-template-suffix-page-list-collections.