Impassibility is part of God’s immutability (changelessness) such that he is not affected by what happens in the world. It means that God is not subject to passions such as pain and suffering, i.e., those things which act upon him and with which he has no control. God is not acted upon, but he acts upon us. However, this does not mean that God has no passions in the sense that he has no love or compassion. He certainly does and he expresses them to us.