A creche is a representation of the scene of Jesus Christ’s birth. It's the nativity scene that is displayed at Christmas, with the manger, Mary, Joseph, and the three wise men.
Although a creche is the same thing as a nativity scene, if you want to get nit-picky, the creche refers specifically to the baby Jesus in the manger. Crèche is a French word that also refers to a nursery or daycare center. Say creche to a British person and she’ll assume you’re talking about a daycare, 'cause that's what they call it across the pond.