You can make explicit why Isaac built an altar. Alternate translation: "Isaac built an altar there to sacrifice to Yahweh" (See: [[rc://en/ta/man/jit/figs-explicit]])
To "call on" means to pray or to worship. Here "name" stands for Yahweh. Alternate translation: "prayed to Yahweh" or "worshiped Yahweh" (See: [[rc://en/ta/man/jit/figs-metonymy]])