Nor do we seek God, unless He is first at work within us to lead us to do so. U stands for unconditional election. If sinners are as helpless in their depravity as the Bible says they are, unable to know and unwilling to seek God, then the only way they could possibly be saved is for God to take the initiative to change and save them. This is what election means. It is God choosing to save those who, apart from His sovereign choice and subsequent action, certainly would perish.
L stands for limited atonement.
No, the question rather is what is the purpose of Christ's death, and what did He accomplish by it. Reformed theology stresses that Jesus actually atoned for the sins of those the Father had chosen. He actually turned aside the wrath of God toward His people by taking their judgement upon Himself, actually redeemed them, and actually reconciled those specific persons to God. I stands for irresistible grace. Left to ourselves, we resist the grace of God.