ouvrage means “book” | MotiTan French Dictionary

More examples

Je vais emprunter un ouvrage à la bibliothèque.

I am going to borrow a book from the library.

A substantial written work assembled into a coherent whole.

livre: A published, bound book, such as a novel or textbook.
bouquin: An informal term for a book read casually or bought secondhand.

Une œuvre écrite publiée, englobant les livres savants, les traités et les recueils destinés à la diffusion.

Ouvrage developed in Old French from ouvrer, 'to work', with the suffix -age, linking the noun to the idea of a made work.

Ouvrage is masculine, so the phrase is un ouvrage, and cet ouvrage uses the vowel form of the demonstrative.