Sovereignty means rule, and the sovereignty of God means that God rules over His creation with absolute power and authority. He determines what is going to happen, and it does happen. God is not alarmed, frustrated, or defeated by circumstances, by sin, or by the rebellion of His creatures. Nor does He violate the free will of His creation. The Doctrines of Grace.
T stands for total depravity.
This does not mean that all persons are as bad as they could possibly be. It means rather that all human beings are affected by sin in every area of thought and conduct so that nothing that comes out of anyone apart from the regenerating grace of God can please God. As far as our relationships to God are concerned, we are all so ruined by sin that no one can properly understand either God or God's ways. Nor do we seek God, unless He is first at work within us to lead us to do so. U stands for unconditional election.