Unity can save or Bake the Lights and Lighting data in the scene, and it is commonly done on mobile games to save on computations. Have you ever played a game where a light source is moved or destroyed, but the lighting effect stays in place? That is because the light was Baked and had the data stored to optimize it.
A Light Probe is a point that holds the recorded light data at that point in space. The Light Probe is part of a Light Probe Group component attached to any GameObject, but it is best to create the group as a separate GameObject.
You can edit the Light Probe Group to move and create more Light Probes. See the complete documentation here.
The Light Probe’s primary function in Unity is to store Baked Light data from non-moving or Static light sources at the given point that is then used to apply that light data to moving or Dynamic objects in the scene.