Consider a prismatic bar loaded in tension as shown. I consider a point Q in the bar away from the ends. This point Q can be considered as an infinitesimally small element taken within the body.
We can consider many different elements, representing point Q, which correspond to different rotations about the axis perpendicular to the plane of the screen. On each of these elements the stresses will be different and since we can obtain infinite number of elements by rotating at different angles we can have infinite number of stresses. Since all the elements correspond to point Q does that mean there are infinite number of stresses acting at point Q?