The Japanese word オブジェ means something like “avant-garde sculpture”, it does not apply to things like classical sculptures or 18th century busts. Most modern art sculptures are called オブジェ by Japanese people. I am not totally sure オブジェ is always art, as a decorative interior dead tree with no further processing can also be an オブジェ.
I can't find an equivalent word in French, is there any?
Google Images might give you a better idea of what it is used for.
Strangely, the word actually comes from the French “objet”.