Here the word "heat" describes the word "sun." The people suffering from the sun's heat is spoken of as if the heat struck them. Alternate translation: "nor will they suffer from the sun's heat" (See: [[rc://en/ta/man/translate/figs-hendiadys]] and [[rc://en/ta/man/translate/figs-metaphor]])
Yahweh speaks of himself in the third person. He speaks of protecting the people and caring for them as if he were their shepherd. Alternate translation: "I, the one who has mercy on them ... I will guide them" (See: [[rc://en/ta/man/translate/figs-123person]] and [[rc://en/ta/man/translate/figs-metaphor]])