Whoever restrains his words has knowledge, and he who has a cool spirit is a man of understanding. Even a fool who keeps silent is considered wise; when he closes his lips, he is deemed intelligent (Proverbs 17:27-28 ESV).
Wisdom is knowing when to speak and when to keep silent. It is keeping cool when everyone else is red hot and emotionally charged. It is listening instead of responding. Wisdom pays attention to the spirit behind the words and reacts according to that spirit-opposite of a negative one and likewise with a positive one.
Life and death are in the power of our tongues. Always speak life and choose wisdom.