Line to shape
Gives a line a width and turns it into a shape the machine cuts round. A drawn line has no width of its own, so this is how a 4mm slot for a 4mm panel gets cut to size instead of coming out at whatever the beam happens to be.
A line on its own has no width. The machine follows it and leaves a kerf, and the kerf is not a measurement you chose.
Say how wide it should be, measured across the line.
Now it is a closed shape with two sides, and the beam goes round it. A closed outline becomes a frame with an inside and an outside instead.
Every setting
2What each number in the dialog means, and where it starts.
How wide to make it, measured across the line.
Leave the original lines in place as well.
What it is
Gives a line a width and turns it into a shape the machine cuts round. A drawn line has none of its own, so this is how a 4mm slot gets cut to size.