Amber is a type of fossil. It used to be resin, a type of sap that comes out of trees. Over millions of years, the resin hardened from a thick liquid into a solid. It looks like a clear, golden rock or stone. Sometimes, insects or plants got stuck in the resin while it was still a liquid. They fossilized with the amber, and so in some pieces, you can see the insects frozen inside.
Would amber fossils be considered trace or body fossils? They would be considered body fossils, because they preserve pieces of animals or parts of a plant, not the behavior of either.