PsychoPy uses a number of different units for position and size.
norm is good for text. Your screen is 2x2 norm units.
height is good for online. Your screen is 1 height unit tall and 1.6 units wide. The width depends on your aspect ratio.
pix can be simple to use locally when you don’t want to calculate the aspect ratios of your images.
cm only works offline and needs you to tell PsychoPy the dimensions of your monitor.