The DPI is the step interval that you can find in the layer parameter setting.
if you set it as 0.5 it will 1 mm of advance in 2 steps, there you can see the lines , if you set it 0.01 or 0.005 you are increasing the "DPI" here it means that the lines will be closer and more detailed. the speed and the power will give you the deep of the engrave that in this case combined with the step interval will get the apropriate DPI