en_tn/pro/31/26.md

opens her mouth with wisdom

The act of opening her mouth is a metonym for speaking. The abstract noun "wisdom" can be translated as an adverb or an adjective. Alternate translation: "she speaks wisely" or "she speaks wise words" (See: rc://en/ta/man/translate/figs-metonymy and rc://en/ta/man/translate/figs-abstractnouns)

the law of kindness is on her tongue

The phrase "on her tongue" refers to her speaking, as the tongue is part of the mouth. The phrase "the law of kindness" refers to her teaching people to be kind. Alternate translation: "she teaches people to be kind" (See: rc://en/ta/man/translate/figs-metonymy)