Drilling is repeated practice of a movement until it becomes automatic. The same thing, over and over, until you stop having to think.
Armies, orchestras and language classes all use it, and drilling vocabulary means running through it until recall is instant. It has a poor reputation in education, since drilling without understanding produces people who can recite and not apply, but for anything that must be fast under pressure it remains unbeatable. There is a completely separate sense from boring holes, so oil drilling and drilling into a wall are the same word doing a different job.
Middle Dutch
drillen — bore, move in a circle
English
drill
English, today
drilling
From drill + -ing. drill comes from Middle Dutch drillen (“bore, move in a circle”).
Etymology from Wiktionary, CC BY-SA