Every parable that is taught within the scriptures is used as a way to show others eternal truths. Within a few chapters of Luke (16-18), many parables are taught that are meant to help us gain knowledge on various eternal truths.
In Luke 16:1-12, the Parable of the Unjust Steward is given. The truth that should be learned from this parable is that we should start to prepare for an eternal future, one after death, instead of the Earthly future most people will prepare for. As we do this, we can increase our faith in the Lord and not worry as much about the worldly things.
In Luke 16:19-31, the Parable of the Rich Man and Lazarus was given. The truth we should learn from this is that, in the world after this life, there are two separate places, paradise and spirit prison. But, even though there are two places, Christ bridged the gap between them in order to help those in spirit prison find their way to paradise.
In Luke 17:11-19, the Parable of the Ten Lepers was given. We learn that all are equal in the sight of God, and we need faith in Him in order to truly be healed. Once we are healed, we should thank our Heavenly Father, and become humble before Him.
In Luke 18:1-8, the Parable of the Unjust Judge is given. We can learn, from this parable, that the Lord wants us to pray, and to not expect to be so easily forgiven in order to stay away from those things that made us sin in the first place.
In Luke 18:9-14, the Parable of the Pharisee and the Publican is given. The eternal truth that can be learned from this parable is that we need to be humble as we pray, and not look at self-righteousness as an assurance that we are doing all that is right. God wants us to be humble, meek, and submissive.
All of these truths can help us learn those things that will help us grow and become a better Child of God, if we allow the truths to help us. The Lord has given us these parables to learn from, so we need to take the time and effort to study them and find what the Lord wants to teach us. As we do so, we can increase our faith and love in the Gospel, and in the Savior.