en_tn_condensed/psa/125/002.md

As the mountains surround Jerusalem, so Yahweh surrounds his people

Yahweh's protection is spoken of as if he was the mountains surrounding Jerusalem. Jerusalem was surrounded by several mountains, which protected it from attack. Alternate translation: "As the hills that surround Jerusalem protect it, so Yahweh protects his people" (See: rc://en/ta/man/jit/figs-simile)

now and forever

Here, this phrase means "always." (See: rc://en/ta/man/jit/figs-merism)