The Hebrew word translated secret is simply ‘session’. Here is something which is known to some people who have met in session or in council.
The application to the church is that a supportive person will be willing to see his offending fellow believer in the best possible light. If he commits a fault, he will be credited with sincere repentance and good intentions. He will be regarded as a child of God, and the best possible construction will be put on his conduct. The talebearer wants to destroy, but the supportive person wants to see the fault put away, and the offender forgiven and accepted.