It is implied here that this refers to dead people. AT: "The corpses of both the young and the old lie on the dust" (See: [[rc://en/ta/man/translate/figs-explicit]])
These phrases refer to people. These two opposites are used to refer to all ages of people. AT: "Both young people and old people" or "People of all ages" (See: [[rc://en/ta/man/translate/figs-nominaladj]] and [[rc://en/ta/man/translate/figs-merism]])
Here the "sword" refers to their enemies. This is a euphemism that means that they were murdered by their enemies. AT: "My young women and my young men have been murdered by their enemies" or "My enemies have murdered my young women and my young men" (See: [[rc://en/ta/man/translate/figs-euphemism]])
This speaks of Yahweh allowing the poeple to be slaughtered as if he killed them himself. AT: "you allowed them to be slaughtered" or "you allowed this to happen" (See: [[rc://en/ta/man/translate/figs-metonymy]])