Be simplicity itself
Definition 1 of 1
Pro Tip 1/3Ease of Use
The phrase often refers to something being easy to use or understand without the need for special skills. 
Using the new software is simplicity itself; even beginners can master it quickly.
Pro Tip 2/3No Complexities
It implies that the thing being described lacks unnecessary features or complications. 
The design of the app was simplicity itself, with a clean interface and intuitive controls.
Pro Tip 3/3Effortless Understanding
Usually means that something can be understood effortlessly without confusion or needing further explanation. 
Her explanation of the theory was simplicity itself, making the complex topic easy to grasp.