dragon spell isn't a thing, she means spells involving dragons. there is a study of magic called dragon magick, where you call upon the strength and wisdom of dragons for guidance. a quick disclaimer though, i know dragon's don't exist in the physical. dragon's are astral beings, who dwell in the astral plain. for the most part they keep to themselves and aid those who they can tell deserve it. dragon spells are basically calling upon them. a good example is a wealth spell i've found many times where you call upon dragons to aid you gaining more wealth.
most dragon spells, while they can be made, typically come from talking with them in a meditative state, or in the astral. if they feel you are ready, they will give you spells and rituals to follow.