Something multifaceted has many parts, or many sides you can look at. The picture behind the word is a cut gem: each small flat face is a facet, and light hits them differently. We almost never use multifaceted for a real diamond in daily talk. We use it for a person, a problem, a story, a talent, a job: it is not only one thing.

A multifaceted person is not simple — kind at home, sharp at work, funny with friends. A multifaceted problem has more than one cause, so one easy fix will not do. It is a slightly fancy word. In easy English, “it has many sides” is already close.

Though actually, people stretch it. Almost anything a little complicated can get called multifaceted in a report, and then the word thins out to mean only “not simple.” Said of a person, it is still usually a compliment: you are saying there is a lot to them, not that they are messy.