Here the word "covenant" is a metonym for the one who establishes or mediates a covenant. Alternate translation: "I will ... make you be the mediator of a covenant with the people" (See: [[rc://en/ta/man/jit/figs-metonymy]])
Yahweh speaks of making his servant the one who delivers the nations from bondage as if he were making him a light that shines in dark places for the Gentiles. (See: [[rc://en/ta/man/jit/figs-metaphor]])