Do you know what a boomerang is? It's that toy you throw and it comes back. Words are like that. If you say "You're annoying!" to your friend, the boomerang comes back and brings a fight and sadness to you. If you say "You're cool, want to play?", the boomerang comes back bringing joy and company.
The Bible says we "eat" what we say. Whoever says good things and helps out (tidies up the mess) receives good things back (praise, gifts, affection).