en_tn/psa/010/007.md

His mouth is full of cursing and deceptive, harmful words

What people say is spoken of as being in their mouth. AT: "He always curses people and says things that are deceptive and harmful" or "He always curses people, tells lies, and threatens to harm people" (See: rc://en/ta/man/translate/figs-metonymy)

his tongue injures and destroys

Here the tongue represents speaking. AT: or "what he says injures and destroys people" or "he speaks words that threaten and hurt people" (See: rc://en/ta/man/translate/figs-metonymy)