The Terms “Uncountable number”, “Sand on the Seashore”,” Dust of the Earth”, or “Stars of the sky” simply means a very VERY large number and almost uncountable number is being described.
This term could be used to describe a massive amount of people/animals:
Judges 7:12
“The Midianites, the Amalekites and all the other eastern peoples had settled in the valley, thick as locusts. Their camels could no more be counted than the sand on the seashore.”
They are also used to describe a very long period of time or a large amount of something:
Job 29:18
“I thought, ‘I will die in my own house,
my days as numerous as the grains of sand.’”
Job 6:2-3
“If only my anguish could be weighed
and all my misery be placed on the scales!
It would surely outweigh the sand of the seas—…”
Genesis 41:49
“Joseph stored up huge quantities of grain, like the sand of the sea; it was so much that he stopped keeping records because it was beyond measure.”
These are all describing a very large or massive number, now this does not mean these amounts being described are really uncountable; of course, any number (apart from infinity) given the appropriate amount of time and accurate counting can be counted; and of course, God knows how much of something is. This term “Uncountable number” is used to describe a very large number to a human viewer in a particular period of time that is so large that it seems to be uncountable in the moment.
God even uses this term to describe the descendants of Abraham:
Genesis 13:16
“I will make your offspring like the dust of the earth, so that if anyone could count the dust, then your offspring could be counted.”