I'm afraid the jury's still out on that one.
Sage is an upcoming job to appear in Final Fantasy XIV. It is one of the two new jobs to be introduced in the Final Fantasy XIV: Endwalker expansion. The job will focus on healing and using barriers to enhance the defenses of their allies, while using Nouliths to channel aether to attack their foes. They have no base job and will start on level 70.
The nation of Sharlayan is the cradle of knowledge, and the Studium its foremost institution of learning. Yet more so than its incomparable library and formidable assemblage of Archons, this prestigious academy is famed for blending traditionally distinct fields to produce revolutionary new disciplines. Among these, perhaps the most distinguished is an altruistic art which draws upon the wisdom of aetherology, sorcery, and medicine. Dubbed somanoutics, the art seeks to heal and protect by manipulating corporeal aether through the use of nouliths, a flying array of foci. Practitioners are dedicated to the betterment of mankind, and for their wisdom and compassion, eventually came to be known simply as sages.Lodestone
The Sages are classified as a barrier Healer, with unique mechanic of imbuing their spells with Kardia to heal the targeted allies each time they dealt damage. As such, they're expected to attacking consistently, and they have the most variations of damaging spell amongst all Healers. In Endwalker, Alphinaud Leveilleur changes his job into Sage.
Behind the scenes
On July 30, 2021, Naoki Yoshida addressed the players on a lodestone post about a design change regarding the sage's job icon after receiving player feedback from around the world over the icon triggering trypophobia in some players (discomfort when seeing clusters of small holes or bumps). The new job icon has the holes that represent the nuoliths filled in and the two on the outside pointing inwards. 
sage in classical philosophy is someone who has attained the wisdom which a philosopher seeks.A