Hi,

Shearing Stress, is basically defined as the ratio of shear force that is applied along the surface of any body and the area of that surface.

Ex. You deform a cube by its upper surface, but its base it still same.

Shearing strain : It can be defined as the ratio of relative displacement of any layer to its perpendicular distance from the fixed layer.

Ex. You can imagine the same example as above and do the calculations.

Hope it helps.