The phrase "blade gap" refers to the space between the cutting edge of a blade and the surface or material it is cutting. It is the distance or gap between the sharp part of the blade and what it is cutting. Full definition
Usually this includes a smaller blade gap that exposes a small amount of the double - edge blade. (shaving101.com)
After closely examining the razor, it looks like there is a larger blade gap, thus making it slightly more aggressive as a good amount of the blade is exposed. (primandprep.com)
The smallest blade gap is set at 1; the most aggressive is 6. (mistershaver.com)