The cube (キューブ, Kyūbu) is a vehicle that can travel freely any where in the universe and between other universes.
The cube is the vehicle of the gods. It can be used to travel anywhere in the universe and can also go to other universes. Champa has a cube and it is promised to Hit by Vados if he wins the tournament. This cube is also used to transport Team Universe 6 and their guests to the Nameless Planet. Whis uses another cube to transport Team Universe 7 and their guests to Beerus' planet to pick up Beerus and Monaka and then the Nameless Planet for the tournament.
During the Universe 6 and Universe 7 tournament, Hit has lost in interest in obtaining the cube because of his entertaining fight with Goku so he loses his fight with Monaka on purpose. As a result, Team Universe 6 loses the tournament, declaring Team Universe 7 the victors.