This term has no rigorous definition and is generally something suppliers use because – everyone else is using it. It is usually meant to imply that the format of reports can be very precisely controlled – typographically, page size, graphics, colours and so on.
In fact the ability of BI platforms which claim pixel perfect reports, varies enormously. Some have very advanced control of page size and typography, and some have almost none. So it really is a term that means very little, and if report formatting and printing quality is important then suppliers need to be looked at individually.
The term has been used in gaming and in the distant past as a means of stating that the resolution of an image matched the resolution of a monitor – but these meanings are pretty well lost to history now. In reality the standard that needs to be met is that set by products like Adobe Illustrator, and other publishing software.
However none of the BI platforms we are aware of come anywhere near, and if very high quality printed reports are necessary, then this is the type of software that will be needed for finishing.