the word of Yahweh that Elijah had spoken

"what Yahweh had told Elijah that Elijah had spoken"

in the second year of Jehoram son of Jehoshaphat king of Judah

This describes the time that Joram began to reign over Israel by stating how long Jehoram had been reigning over Jerusalem. Alternate translation: "in the second year that Jehoram son of Jehoshaphat was king of Judah" (See: rc://en/ta/man/translate/figs-explicit and rc://en/ta/man/translate/translate-ordinal)