HMI means Human Machine Interface
It is like a TV screen with Pictures of Push Buttons that really work the machine when you press the buttons.
You are the Human, and the TV Screen is the Machine Interface.
So to design the Button say (Make Turntable Go On) push the button and then the PLC (programmable Logic Controller ) (Computer with wires attached to the motor or to the turntable will start the turntable)
So if the parts have a pick and place from the parts bin to pick up the parts and put on each station of the turn table, then the second pick and place will put the second part on top of the first part after of course the turntable rotates, etc......
Eventually you got four or five acres under roof and Tanks with Treads are rolling off the Assembly line.
(Prerequisite HMI 101) (you call also get HMI 103)