1080p is a popular high definition resolution video format. The name refers to 1080 rows of pixels that make up each frame. A full high resolution video would be 1920 pixels across x 1080 pixels down.
The “P” stands for progressive, which means that each frame is a complete image, as opposed to an interlaced video which uses every other row of an image (and alternated between the next frame) and is referred to as 1080i.