In 1:15-17 the singular pronoun "he" and "his" refer to a Babylonian solider who represents all of the Babylonian soldiers. These pronouns can be stated as plural. Alternate translation: "They bring ... they continually slaughter" (See: [[rc://en/ta/man/translate/figs-123person]] and [[rc://en/ta/man/translate/figs-synecdoche]])
Habakkuk asks this question because he is frustrated and wants to know how long Yahweh will allow the Chaldeans to continue to destroy people and nations. Alternate translation: "Will you therefore let them empty their fishing nets and continue to slaughter the nations while they feel no compassion?" (See: [[rc://en/ta/man/translate/figs-explicit]])
Habakkuk speaks of the Chaldeans preparing to conquer more nations as if they were fishermen who empty their nets so that they can use them to catch more fish. (See: [[rc://en/ta/man/translate/figs-metaphor]])