God has made known some of His Secrets* to His Servants (prophets & saints):
“that is, the mystery which has been hidden from the past ages and generations, but has now been manifested to His saints,” (Colossians 1:26)
“Now to Him who is able to establish you according to my gospel and the preaching of Jesus Christ, according to the revelation of the mystery which has been kept secret for long ages past,” (Romans 16:25)
“and to cause all to see what is the fellowship of the secret that hath been hid from the ages in God, who the all things did create by Jesus Christ,” (Ephesians 3:9)
“but we speak the hidden wisdom of God in a secret, that God foreordained before the ages to our glory,” (1 Corinthians 2:7)
*The Greek word (original) for “secret” is ‘same’ as ‘mystery’ too. It probably means more accurately, a “mysterious secret” in “meaning” though it doesn’t occur like that (adjective – noun pair) in the original manuscripts.