Two separate vellum leaves from a Book of Hours by Philippe Pigouchet for Guillaume Eustace, produced sometime between 1488 and 1518. One leaf is in French illustrated with a hand-painted woodblock printing of two very finely detailed centaurs, representing the sign of the zodiac Sagittarius, and a family crest. The verso of this leaf gives information about the movement of Easter each year and includes strawberries and arabesques in blue and painted gold in the marginal decoration and the text surrounded by a painted gold border. Rulings are visible. The second leaf is in Latin with both sides including marginal decorations of arabesques and flowering plants, and the text surrounded by a painted gold border. Rulings are visible.

Date us approximate. 

A leaf is the term used to describe a single sheet of parchment which typically has 2 pages of text and/or illustrations, front and back.