This means that he lived in a way that pleased Yahweh as his father had done. Here "walking" is an idiom for the way a person lives and behaves. Alternate translation: "He did things that were pleasing to Yahweh, like his father Asa had done, and he did not stop doing those things" (See: [[rc://en/ta/man/translate/figs-explicit]] and [[rc://en/ta/man/translate/figs-idiom]])
The eyes here represent seeing, and seeing represents judgment. Yahweh saw and approved of Jehoshaphat's actions. See how you translated a similar phrase in [2 Chronicles 14:2](../14/02.md). Alternate translation: "he did what Yahweh judged to be right" or "he did what Yahweh considered to be right" (See: [[rc://en/ta/man/translate/figs-metaphor]])