This word is derived from probation:
"Early 15c., "trial, experiment, test," from Old French probacion "proof, evidence" (14c., Modern French probation) and directly from Latin probationem (nominative probatio) "approval, assent; a proving, trial, inspection, examination," noun of action from past-participle stem of probare "to test" (see prove). Meaning "testing of a person's conduct" (especially as a trial period for membership)." - Online Etymology Dictionary
In esotericism, probation is how the mind is tested through ordeals, difficulties, trials.
"Probationism is the science of esoteric ordeals." - Samael Aun Weor, Christ's Will
The ordeals given to a student are directed and overseen from the internal worlds, not the physical world.
"Everyone who follows the path of the Perfect Matrimony should live alert and vigilant as a watchman in the time of war, because during the hours of sleep the masters test their disciples. Yet, the tenebrous ones attack us during sleep when we are working in the Great Work. Thus, during sleep, we have to pass through many ordeals in the Internal Worlds. When the masters are going to test the disciple in something, then they awaken the disciple’s consciousness." - Samael Aun Weor