en_tn_condensed/psa/145/021.md

My mouth will speak

Here the words "My mouth" represent the one speaking. Alternate translation: "I will speak" (See: rc://en/ta/man/translate/figs-synecdoche)

will speak out the praise of Yahweh

"tell everyone how good Yahweh is"

let all mankind bless his holy name

The word "name" is a metonym for Yahweh himself. See how "may his glorious name be blessed" is translated in Psalms 72:19. Alternate translation: "let all people bless him" or "let all people do what makes him happy" (See: rc://en/ta/man/translate/figs-metonymy)