Hey there ! Welcome in the 3d printing world !
Actually your nozzle size is probably 0.4 if it's a stock A8.
0.2 is the layer height resolution in the slicer so it will be the height of each layer of material. Smaller give a nicer finish and bigger print faster but with less finish and bigger tolerances for dimensions. That you use 0.2mm layer heigh is not a requirement it's just to give an idea of the parameters I printed with.