From Latin 'lectio' (a reading) via French — in the medieval world, learning meant being read to.
A period of learning or teaching, or an experience from which something useful is learned.
From Old French 'leçon,' from Latin 'lectiōnem' (accusative of 'lectiō'), meaning 'a reading, a selection read aloud,' from the past participle 'lectus' of 'legere' (to read, to gather, to choose, to collect). The PIE root is *leǵ- (to collect, to gather, to speak). In medieval Christian liturgical practice, 'lectiō' referred specifically to a passage of scripture or hagiography read aloud during the divine office or the Mass — the congregation's daily 'lesson' was literally the passage read to them by a lector. The word thus enshrines the ancient equation between reading and learning, and between listening
A 'lesson' is etymologically 'a reading' — from Latin 'legere,' to read. The same root gave us 'lecture' (also a reading), 'legend' (something to be read), 'legible' (readable), 'elect' (to choose out), and 'collect' (to gather together). Reading, choosing, and gathering were all the same verb to the Romans.