Man is sinful, and when the Scriptures speak of man “repenting” it is in reference to him changing his mind and turning from sin. It means to “confess and forsake” his sins.
However, Numbers 23:19 tells us that “God is not a man, that He should lie, nor a son of man, that He should repent.”
God is without sin, so any reference to God’s “repentance” is merely His relenting by not bringing about a promised punishment if sinners turn from their sins. The King James translation has at least twenty-six references to God “repenting,” and each time it is in the context of punishing or rewarding a person or group of people. For example, Jonah 3:10 says, “Then God saw their works, that they turned from their evil way; and God relented [“repented, KJV] from the disaster that He had said He would bring upon them, and He did not do it.” Because He did not punish them as He warned, it may appear to them that He “changed” His mind, but His punishment was contingent on their repentance.
Jeremiah 18:8 if that nation against whom I have spoken turns from its evil, I will relent of the disaster that I thought to bring upon it.