Title says it all. Like a christmas tree ornament, what would you call it?
“Décorations“, “Décorations de Noël” are the words we use about christmas tree ornament.
and as Joubarc stated in his commentary:
[...] it's not limited to Christmas either. Note the singular is décoration; ornement also exists but isn't used much nowadays and mostly for immobile stuff (statues in a park, for example).