what type of blade is beveled on one side and straight on the other
Razors come in two varieties, dual bevel or single bevel. They are identified by whether both sides are angled, which creates a side-view like an isosceles triangle, or just single-angled. The single-angled is straight one one side and angled on the other. When talking about sharpening blades to a particular angle, the sharpening needs to occur equally to both sides of the dual-angle blade. For instance, the ideal shave is achieved with a 15 to 20 degree bevel angle.
There are special cases where the total angle of the knife is not double the angle that you sharpen each side of your knife. Some traditional Asian knives are only beveled on one side. In this example, one side may be sharpened to 20 degrees while the other side is at 0 degrees for a total angle of 20. However, in practice, we have found that the vast majority of Asian knives sold in the United States are not single bevel but rather traditional knives with a bevel on both sides.