CAM software is what you use to program the machine to do the things you want it to do. It’s that transition from drawing to machining.
You use CAM software to program the CNC to say, drill holes at the points in your drawing where you expect holes to be drilled. With modern CAM software you’s specify the procedure you want to program for ( a hole drilling process for example). You then may have some choices from a list of different drilling processes like Tap, where the bit will drill a little ways down, lift up, drill a little farther down, lift up.