Multifaceted means having many aspects or sides. Diamonds are usually cut to be multifaceted, that is, with many angled flat surfaces, because this increases their ability to reflect light.
Since facet means "aspect," "side," or "face," multifaceted means "many aspects, sides, or faces." This can apply to jewels or other physical objects, like the eyes of a dragonfly, but it can also refer to complicated issues that have lots of contributing factors and generate more than two sides to an argument. A multifaceted person has many abilities, or a personality with many sides to it.