The biens nationaux were properties confiscated during the French Revolution from the Catholic Church, the monarchy, émigrés, and suspected counter-revolutionaries for "the good of the nation". Biens means "goods", both in the sense of "objects" and in the sense of "benefits". Nationaux means "of the nation". The phrase is in middle French form, and is in the nominative case, so it literally means both "national things" and "benefits for the nation". This can be summarized as "things for the good of the nation", or simply "national goods".