what happens to light when it travels from air into glass at an angle of incidence of 0?

i think you mean an angle of incidence of 90, because its impossible to go into something at an angle of 0. if i am right, and the glass is plane then the light just goes straight through and is not refracted

The direction of the light beam does not change, but it does slow down slightly. The speed of light in glass is not quite the same as the speed of light in a vacuum.

ADDED: I am also assuming that the light beam strikes the surface in a direction normal to the surface.

in the case of a normal incidence (the incident ray makes an angle pi/2 with the surface on which it is incident) the direction of propagation does not change (no refraction takes place) the propagation speed in glass becoming c(glass)=c(vacuum)/n where n stands for the refraction index of glass (n>1; c(glass)<c(vacuum)