In this verse, Paul explains that as children, we are subject to guardians and managers until the time appointed by the father. Paul uses this analogy to illustrate how humanity was in a state of spiritual immaturity and bondage to the Law before the coming of Christ. But through faith in Christ, we have become sons of God, and the Law has served as a tutor to lead us to Him so that we might receive the full rights of sonship.
Paul compares those who seek justification through the Law to an immature child who needs a caregiver. The Law serves as a caregiver to instruct and guide the immature, but it can never bring about full spiritual maturity or justification. Rather, only through faith in Christ can a person be justified and made righteous before God.
Those who attempt to follow the Law are like children who inherit a great legacy but are too young to enjoy its benefits. No matter how great the inheritance may be, until they come of age, they are no better than slaves. Similarly, those who are not bound by the Law but are justified by grace through faith in Christ have reached spiritual maturity and received the promise of Christ Jesus our Lord, who gives us victory in this life and great rewards in heaven.

Dear Heavenly Father,  I thank You that through faith in Christ, I am no longer a slave to the Law. I am grateful that You have adopted me as Your own child, and I can now call You "Abba Father." Help me to understand and mature in my faith so that I can receive the full benefits of my inheritance in Christ. May I always trust in Your grace and not my own works, and may Your Holy Spirit guide me to walk in the victory that Christ has secured for me. 
In Jesus's name I pray. Amen.