Although named point for historical reasons, this light source can model light either from a (theoretical) point source, or from a sphere (the latter being more realistic in most cases, and producing less sharp shadows). The light is cast evenly in all directions.
The Lights page has more detail about the controls. In addition to honoring the standard Maya light attributes, the Attribute Editor will also show the following attributes under the Arnold group:
The radius of the light's spherical surface. Although the name of this light is 'point' for historical reasons, it really is an emissive sphere, unless radius is set to zero, in which case it becomes a true point light of no physical size.