1920x1080, a standard resolution for high-definition video
1080p indicates 1920x1080, a standard resolution for high-definition video. Commonly used for televisions and some widescreen computer monitors.
'1080' indicates the vertical resolution, and the 'p' indicates that the video is not interlaced (i.e. each frame has the full 1080 lines of vertical resolution).
Compare 720p and 1080i.