Meaning

noun a collection of objects laid on top of each other

noun (often followed by `of') a large number or amount or extent

noun a large sum of money (especially as pay or profit)

originFrom French pile (“battery”), with the pronunciation adapted to the existing English word pile. Doublet of Etymology 1, which may have influenced the sense development by emphasizing the stack (“pile”) out of which early batteries were made.

Etymology from Wiktionary, CC BY-SA 3.0