Time orbs were fragments of a time ship's drive system.
When the engine of the time ship of the Jones family had exploded, the time orbs fell through time along with the Joneses. Since the Eleventh Doctor wanted to use the time orbs for repairing the ship he told Amy to collect them. Later the Daleks tried to force the Eleventh Doctor to give the time orbs to them by kidnapping Mrs Jones and threatening to destroy Earth. The Doctor saved Mrs Jones and the Earth without giving the time orbs to the Daleks. (GAME: The Mazes of Time)