Lacchini is an impact crater on the far side. It is located in the northern hemisphere, just behind the northwestern limb of the visible Moon. This part of the lunar surface can sometimes be viewed under favorable conditions of libration and illumination, but at such times the crater is only seen from the edge. Less than one crater diameter to the east is the larger crater Bragg. (wikipedia entry)
A crater is a circular depression likely created by an impact event. On the Moon they are named after deceased scientists, polar explorers, astronauts or cosmonauts.