What does RES stand for?

Resolution

This term can describe either how many pixels a monitor can display or how fine a printer can print. 1. Monitors. A small monitor may have a resolution or 640 x 480, which means there are 640 pixels horizontally across the screen and 480 pixels vertically. Some other common monitor resolutions are 800 x 600, 1,024 x 768, and 1,280 x 1,024. The higher the resolution, the more that can be displayed on the screen.