一寸光阴一寸金,寸金难买寸光阴 is a classic Chinese proverb: 'An inch of time is worth an inch of gold, but an inch of gold cannot buy an inch of time.' It teaches the preciousness of time.
usage
In modern usage, 寸 often refers to screen size in inches (e.g., 6.7寸屏幕, a 6.7-inch screen) or photo sizes (一寸照片, a 1-inch ID photo).