This device has a black and white wire, coming out of the outlet is a black, white and ground wire. What do we do with the ground wire? plastic outlet

Leska: I am assuming that you are going to replace a lighting switch with the timer. The black wire and the white wire carry electric current. The ground wire is not used by the switch (or timer). The ground wire should be connected by a screw to the junction box for safety. Leave it as it is.