"Touch buttons" refer to interactive buttons or controls on a device or screen that can be activated by touching them with a finger or a stylus. Full definition
On the front, the design remains the same with the fingerprint scanner / home button along with two capacitive touch buttons on the either side. (droidholic.com)
The phone features a physical home button and two capacitive touch buttons on the front. (droidholic.com)
You can also have a transparent background on home touch buttons in home screen. (phoneradar.com)