The highest resolution of the CG248-4K is 3840 x 2160. That's over four times the resolution of a 1920 x 1080 (HD 1080) PC screen, which is the most common resolution. 1920 x 1080 (HD 1080) is also found on this PC screen.
A 3840 x 2160 graphics resolution is in fact the best resolution amongst all LCD screens that came out in the last year.
Amongst similar types of flatpanel monitor the worst resolution is 640 x 350.