'Firstborn Males' in the Bible

Yahweh said to Moses, "Number all the firstborn males of the children of Israel from a month old and upward, and take the number of their names.

All the firstborn males according to the number of names, from a month old and upward, of those who were numbered of them, were twenty-two thousand two hundred seventy-three.

All the firstborn males that are born of your herd and of your flock you shall sanctify to Yahweh your God: you shall do no work with the firstborn of your herd, nor shear the firstborn of your flock.