“Light Probes” are essentially a coordination of sensors that are able to pick up baked lighting information and relay it to dynamic objects. This means that objects that self illuminate with “Emissions” are able to direct their baked light realistically onto their surroundings by using light probe groups.
By using light probes throughout your scene in coordination with object emissions you have the potential to make your game way more efficient, which means less lag, and faster load times.
To create a “Light Probe Group” you simply have to right-click within the hierarchy and select “Create>Light>Light Probe Group”.
A newly created “Light Probe Group” will consist of 8 probes and resemble a cube with light probes at each corner.
If you select the “Edit Light Probes” from the hierarchy, you can select and manipulate the probes individually, or in groups, if you select them while holding Ctrl or Shift.
While selected, you can hit Ctrl+D to duplicate the highlighted probes. If you do this, you can expand and manipulate the light probe group to encompass entire rooms/areas within your scene as seen in the examples above.