In cura, yes, this is the wall thickness. You will need to set the wall thickness at a multiple of the line width in cura. So if you have .4 for the line width, you will need to set the wall thickness to .8 at least, although, I think cura will let you just tell it how many walls you want.
It’s the number of walls, when he says 2 or more, not necessarily “2mm”.