"than the grains of sand on the seashore." This comparison is an exaggeration used to emphasize an uncountable number. AT: "more than you can count" (See: [[rc://en/ta/man/translate/figs-hyperbole]])
# Against the mothers of young men I will send the destroyer at noonday
This means that Yahweh will send an enemy army to kill young men, which will cause their mothers great sorrow. AT: "At noonday I will send an enemy army to destroy young men and cause their mothers to weep" (See: [[rc://en/ta/man/translate/figs-explicit]])
# fall on them
This is an idiom. AT: "happen to them" (See: [[rc://en/ta/man/translate/figs-idiom]])