Label DPI (or "dots-per-inch") is the resolution at which your labels are printed. Some of the thermal printers or computing hardware you might use are calibrated to use a specific DPI for printing out labels. In most cases, you will never need to change from 300 DPI (the default) since that is the current standard for printing high-quality images and labels.
However, certain hardware configurations and pairings need a different DPI. For instance, you will need to change this setting (203 DPI) if a Zebra LP 2844 thermal printer is set up to print from a Mac.
All our articles about setting up printers include instruction for how to change this setting (if such a change is necessary). If these articles do not instruct you to change the setting, leave it at 300 DPI.