en_tn_condensed/psa/089/005.md

The heavens praise

Here "heavens" represents those who are in heaven. (See: rc://en/ta/man/jit/figs-metonymy)

praise your wonders, Yahweh

"praise you, Yahweh, because of the wonderful things you do"

your truthfulness is praised in the assembly of the holy ones

The abstract noun "truthfulness" can be stated as "you always do what you promise to do." This can also be stated in active form. Alternate translation: "The assembly of the holy ones praises you because you always do what you promise to do" (See: rc://en/ta/man/jit/figs-activepassive and rc://en/ta/man/jit/figs-activepassive)

the assembly of the holy ones

This refers to the angels in heaven.