This is the documentation for Enlighten.
6. Lightmaps and light probes
Enlighten lights actors using either lightmaps or light probes. Let's see how these work.
- Make sure the View Mode is set to Lit.
- From the Show menu, select Use Defaults to make sure you're seeing the level normally.
- In the World Outliner, select the DirectionalLight.
In the Details pane, under Transforms, set the Rotation to X: 0.0, Y: -50, Z: -150.
This angles the sun so that less of the level is lit with direct light. This will make the effect of the indirect lighting provided by Enlighten easier to see.Before After 
- To see the lighting mode for every actor in the level, in the Show menu, select Enlighten > Lighting Mode.
The colors in the level change to show the different lighting modes.
- Change the View Mode to Unlit.
This hides all the lighting, making the coloration in Enlighten Lighting Mode more obvious.
Meshes lit with lightmaps are orange. Lightmaps are good for meshes with large continuous surfaces, such as walls or the ground.
Meshes lit with probes are green. Probe lighting is good for complex meshes such as trees, characters and small objects.
Meshes that share lightmaps with nearby meshes are blue. This is covered in the next tutorial. Change the View Mode back to Lit to restore the lighting.
From the Show menu, select Use Defaults to show the level with the default editor visualizations.
In the World Outliner, double-click the actor Props_LampPost2 to focus on it.
Notice there are no obvious lighting inconsistencies across actors that use different lighting modes, such as the lampposts and trash bags (which use light probes) and the ground and walls (which use light maps).