Each of the sliders controls one of the six services of the robotic arm (Turn on / Turn of a led, move base, move wrist, elbow move, move shoulder, move clamp).
Move each of them to define the right mix of movements in which you want to place the robotic arm.
Once they were fixed, click "Apply changes" to send the movements to robotic arm and it starts moving up the desired position.
You are moving motors controlling remotely.
You can help yourself with the ILS created for this lab: http://www.golabz.eu/spaces/how-robotic-arm-works