The two phrases refer to the same thing. Together they emphasize that the covenant will endure forever. Alternate translation: "an agreement forever" (See: [[rc://en/ta/man/translate/figs-parallelism]])
"a covenant made with salt." Salt represented permanence and was used in offerings and covenant meals. Alternate translation: "a permanent covenant" or "an everlasting covenant" (See: [[rc://en/ta/man/translate/translate-symaction]])