A 'facet' is a face or side of something with many sides or a feature or aspect of something. So you can talk about facets of a persons personality for example or an interesting or hidden facet of something.

1. The selfish side of Robert is just one facet of his personality. He's actually a good guy when you get to know him.
2. One positive facet of living in this area is the multicultural aspect of this part of the city.

1. There are many facets to Kate's management style, but the most important is her ability to organize and motivate her staff.
2. We should consider every facet of this problem before we attempt to come up with a solution.

1. The company decided to take a multi-faceted approach to dealing with the problem, as they felt that it was too complex to address in any one way.