"And with Him is the knowledge of the Hour," meaning the knowledge of the coming of the Hour; none other than He knows the knowledge of its coming.
﴿وَعِندَهُ عِلْمُ السَّاعَةِ﴾ علم مَجِيء السَّاعَة، لَا يعلم علم مجيئها غَيره.