Akumina is a UI layer built on top of SharePoint. The reason it is used is some clients are not satisfied with what SharePoint provides in terms of being mobile friendly.
Akumina is responsive and works well on smartphones. And the good thing about Akumina is that it has a manager app known as Akumina Interchange which provides a way to manage the Image Slider, Quick links, Announcements list all in one place.
If you want to get adventurous and play with the colors and themes, one can do that by modifying the CSS files in the style library.