I assume that your work material left bottom edge is located at X & Y =0 in the attached pic.Line N220 defines the origin for your Gcode at X & Y =0 and line N230 is the first move for the X & Y axes in the program code.
Now understand the following, and if you don't, do some study on how to set up for a job.
Mach3, the controlling software, needs to know where the actual / physical Machine Zero is. On start up Mach3 keeps track of where the axis is using machine coordinates at all times. When you reference the machine, the user is defining to Mach3 where physical x & y zero is.If you reference the machine and are not at X & Y zero, then you need to define to Mach3 where the material / part is. A work offset is some distance from Machine Coordinate 0,0. Now understand that Mach defaults to G54 offset on start up. Also undestand that G54 work offset, machine coordinate 0,0 and Work coordinates can all be at 0,0 if so desired.
Confused .....? Go study.
RICH