"than the grains of sand on the seashore." This comparison is an exaggeration used to emphasize an uncountable number. Alternate translation: "more than you can count" (See: [[rc://en/ta/man/translate/figs-hyperbole]])
This means that Yahweh will send an enemy army to kill young men, which will cause their mothers great sorrow. Alternate translation: "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]])