The bleed is a 3mm section that surrounds the edge of the printed dimensions. All images, text and colour fills that are intended to extend to the edge of the page should be extended 3mm to create a bleed.
It is very important that you consider the bleed when printing text, boxes and other elements so that they are not cut off when the print is finished. To avoid this from occurring, ensure that these elements are positioned within 6mm from all the edges.