Monochrome is a value scale of a single color, ranging from light to dark. Imagine 11 different values of greyscale. Value 0 is white, 10 is black, and 5 is midway between. The other values are evenly spaced to show a progression from light to dark.
This greyscale bundle has values 0, 2, 4, 6, 8, and 10 and comes to you from Robert Kaufman, including 6 fat quarters of Kona Cotton Solids: