What are the values of angle of incidence i and angle of reflection r for a normal incidence?

Normal is a perpendicular line drawn on a mirror surface.

Angles of incidence and reflection are calculated with respect to the normal.  For normal incidence, the incident ray is along the normal itself. So the angle of incidence is 0.

From the laws of reflection, the angle of incidence is equal to the angle of reflection. So, the angle of reflection is also 0.

So, for normal incidence:

angle of incidence i = angle of reflection r = 0