That is Eldin, the Fire Dragon. As the
Eldin is one of the three Dragons who reside in the three provinces in Skyward Sword. This is the Dragon who resides in the Eldin Province, more specifically, Eldin Volcano. He will teach Link the second part of the Song of the Hero (which he plays on the Goddess's Harp). Like Faron, the Water Dragon, and Lanayru, the Thunder Dragon, Eldin's official title is the Fire Dragon. Eldin will be met towards the end of the game after completing the Bokoblin Base and serves a very important role in the development of the story.