Drop shadow effect
Add a drop shadow under your object visible on the layer.

The Distance and Rotation properties together set where the shadow is cast: rotation gives the direction (in degrees) and distance how far the shadow is offset from the object. Use Blur to soften the shadow's edges. Enable Shadow only to hide the object and keep just its shadow, which is useful to render a shadow on a separate layer or to build silhouette effects.
Reference
All effects are listed in the effects reference page.