en_tn/rom/03/13.md

Their ... Their

The word "their" refers to the "Jews and Greeks" of Romans 3:9.

Their throat is an open grave

The word "throat" is a metonym for everything that people say. Here "open grave" is a metaphor that refers to the stench of dead bodies, a metaphor for the evil words of the people. (See: rc://en/ta/man/translate/figs-metonymy and rc://en/ta/man/translate/figs-metaphor)

Their tongues have deceived

The word "tongues" is a metonym for the false words that people speak. Alternate translation: "People speak lies" (See: rc://en/ta/man/translate/figs-metonymy)

The poison of snakes is under their lips

Here "poison of snakes" is a metaphor that is used to represent the great harm of the evil words that the people speak. The word "lips" refers to the words of the people. Alternate translation: "Their evil words injure people just like the poison of a venomous snake" (See: rc://en/ta/man/translate/figs-metaphor and rc://en/ta/man/translate/figs-metonymy)