Reflection is the property by which light and other electromagnetic radiation will effectively bounce off a surface. It is most commonly observed in mirrors, in which the light hitting the surface of the mirror will be reflected outwards, resulting in the image seeming to appear on the surface. Similarly color is governed by reflection, some wavelengths of light are absorbed by a surface whilst those which are not will be reflected and observed by the eye, giving the object its colour (eg if wavelengths of red and yellow are absorbed and blue is reflected the object will appear blue).
Under standard conditions on a flat surface the angle of incidence will equal the angle of reflection, that is if a ray hits the surface at a 30 degree angle it will reflect at a 30 degree angle, but the path of the ray will be in the opposite direction. Hence it can be said to have been flipped around the normal (line perpendicular to the surface).