A "simple interface" refers to a user-friendly design that is easy to use and understand. It means that the way you interact with a device or application is straightforward, uncomplicated, and requires minimal effort to navigate. Full definition
Good insurance which has easy online web portal with simple interface. (policybazaar.com)
With smart devices now, they find themselves in the pockets of people who don't normally play video games, and it's a very simple interface. (fortune.com)
The new, flat UI provides simple interface requiring little or no user - training. (conrep.com)