Complex sentence: It is revealed in the pilot that Korra is able to bend both fire and earth in addition to her native element, water, at the age of four, thereby proving her status as the current Avatar to the Order of the White Lotus.
Split into simpler sentences: It is revealed in the pilot that Korra is able to bend both fire and earth in addition to her native element, water, at the age of four. This proving her status as the current Avatar to the Order of the White Lotus.