1080p resolution projectors are often referred to as Full HD (as opposed to 720p). Until recently, 1080p projectors typically referred to home theater projectors. That’s no longer the case as more and more business and education projectors are now higher resolution before and count 1080p as one of those resolutions.
What is 1080p? It’s an image that’s 1920 pixels across, and 1080 pixels down. From a practical standpoint consider it to be 2K resolution (close enough).