Here firstly see what material that cnc router can work on: wood(MDF, Plywood, bamboo etc) , plastic(double color board, sandwich board, ACP, PVC, etc), acrylic, stone(marble, granite, jade etc),...
CNC = Computer Numerical Control
This basically means the router (or welder, or cutter, or whatever tool you want to use) is controlled in either the x/y axis (length and width), or the x/y/z axis...