None of the Echo devices can control Z-Wave devices directly. Some Echo devices can control Zigbee switches and dimmers, as well as connect to Zigbee motion and contact sensors (as mentioned by @JDRoberts and @johnconstantelo.)
Perhaps your co-worker is using a lighting system like Lutron Caseta, which has an Alexa Skill. While not z-wave, Lutron’s Clear Connect protocol is a radio frequency based system. Perhaps he is confused as to the underlying technology his switches use?