Device Settings - LightBurn Software Documentation
This is the origin corner or 0,0 location for your laser. If you have a GCode based system, this is almost always at the front left, regardless of the location of your limit switches.
If you have a DSP laser, like Ruida or Trocen, the origin is usually where the limit switches are placed, and will be the corner the laser seeks when powered up.
If your laser output is mirrored horizontally or vertically, move the dot to the opposite corner, horizontally or vertically, depending on the direction that the output is mirrored, and that will correct it.