Quick answer
Some people carry what they hear. The verse makes discretion a matter of loyalty rather than of technique.
Read both lines
The contrast is between two kinds of person, not two policies. A talebearer is defined by movement, someone who goes about with what they were told, and the harm is in the transit rather than in the truth of the item. The answer in the second line is described as a faithful spirit, which locates discretion in character. Concealing a matter here is not deceit or cover-up; it is the ordinary trustworthiness that makes it safe to tell someone anything, and the book counts that as one of the plainest tests of whether a person can be relied on.
Related: Proverbs 20:19 · Proverbs 17:9 · Proverbs 26:20
New King James Version®, Copyright © 1982, Thomas Nelson. All rights reserved. Full copyright information. Scripture provided by API.Bible.
Go Deeper
If this verse has been used to put weight on you that it was never carrying, ask about it directly.