It means know Allah swt by Allah in the creation, who is Imam AlMahdi pbuh. He pbuh is the manifestation and appearance of Allah in the creation, meaning the manifestation and appearance of the City of Divine Perfections amongst the creation.
Ahmed Alhasan is the successor and messenger of Imam Al Mahdi (a.s)
It means know Allah swt by Allah in the creation, who is Imam AlMahdi pbuh. He pbuh is the manifestation and appearance of Allah in the creation, meaning the manifestation and appearance of the City of Divine Perfections amongst the creation.