What does this app do?
You touch it to go Ping or you can shake it to go Ping. The faster you touch and shake the faster it goes Ping.
Now seriously, what is a Mother Box?
Created by Apokoliptian scientist Himon using the mysterious Element X, they are generally thought to be sentient, miniaturized, portable supercomputers, although their true nature and origins are unknown. They possess wondrous powers and abilities not understood even by their users, the gods of New Genesis. These range from teleportation (they can summon Boom Tubes) to energy manipulation. Mother Boxes have been seen healing the injured, including Darkseid himself, after he was beaten by Doomsday. Metron stated that each Mother Box shares "a mystical rapport with nature". They provide their owner with unconditional love and self-destruct when their owner dies.
To the New Gods, they are common appliances (used much like a PDA on Earth), in as much as a sentient device can be called an "appliance". Other DC characters are given access to them at specific times, when they are in need of aid. Notably, Superman was given one when he went in pursuit of Doomsday, which managed to open boom tubes to take Superman to Apokolips, heal Darkseid (when Superman needed his foe's aid against the Cyborg Superman after he'd taken a serious beating from Doomsday), give Superman a power boost to battle Doomsday in the form of various high-tech weapons such as an ultrasonics gun and a laser sword, used Waverider's gauntlet to send Doomsday to the end of the universe, and healed Superman's injuries (simultaneously restoring his original clothes) at the end of the battle, although this last act drained it of power.
Mother Boxes can only be manufactured by a being born either on New Genesis or Apokolips, and not all of them can do it (at least one on Apokolips failed). This is accomplished through much training. It is implied in the books that the maker's character influenced the successful construction of a Mother Box. This applied to all the Fourth World books created, written, and drawn by comic legend Jack Kirby. Later writers altered the fabrication and capabilities of the Mother Box to include its making and usage to humans and beings from other worlds.
No really, please be sensible?
Okay, basically they're a fictional item in the DC Comics Universe.