What does that pile on your finger mean?

2, stacking, basic meaning: put overlapping things up; Quantifier, used for overlapping things.

3. handprints are lines of fingers. Fingers are formed in the last three months of pregnancy, which is also the formation period of baby's brain, sex organs and heart. The length of our fingers will change with age, but the "finger ratio" will always be the same as when we were born. The relationship between finger length and hormones comes from the uterus: in the last three months of pregnancy, the secretion of estrogen and testosterone is much higher than that in other periods of pregnancy, and the level of maternal hormones during this period will affect the future physical condition of the child.