en_tn_condensed/psa/002/004.md

He ... the Lord

These phrases refer to Yahweh. Yahweh is often called "the Lord" but the words for "Yahweh" and "the Lord" are different.

sits in the heavens

Here sitting represents ruling. What he sits on can be stated clearly. Alternate translation: "rules in the heavens" or "sits on his throne in heaven" (See: rc://en/ta/man/translate/figs-explicit and rc://en/ta/man/translate/figs-metonymy)

the Lord mocks them

"the Lord mocks those people." Why he mocks them can be stated clearly. Alternate translation: "The Lord mocks them for their foolish plans" (See: rc://en/ta/man/translate/figs-explicit)