The Bible has much to say about words and speech, but instead of doing a whole study, I will share a few of my favorites here.
I will let the verses speak for themselves.
A gentle answer turns away wrath, but a harsh word stirs up anger. -Proverbs 15:1
Do not let any unwholesome talk come out of your mouths, but only what is helpful for building others up according to their needs, that it may benefit those who listen. -Ephesians 4:29
But I tell you that men will have to give account on the day of judgment for every careless word they have spoken. For by your words you will be acquitted, and by your words you will be condemned. -Matthew 12:36, 37
Fix these words of mine in your hearts and minds; tie them as symbols on your hands and bind them on your foreheads. -Deuteronomy 11:18