The Trinity is an interesting almost koan-like concept. People not Christian sometimes accuse us of not being monotheistic (as having more than one God). There have been countless attempts to explain it, with varying success.
St. Patrick used the shamrock. It has three leaf parts, but is one leaf. I think that is the simplest, most visual explanation. It is quite successful for many people.
(Before I say anymore, I want to address the inadequacy of language. I know that God is not a guy in a bed sheet, that God contains all that is, both male and female. The Creator births all that is. Using "He" implies otherwise. Using "She" sounds strange and is just as incomplete as using "He." Using "It" sounds impersonal, which God is NOT. So, I will be using "He" as the pronoun, not knowing what else to use. This is the usual socially acceptable pronoun.)
For me, the Trinity is a way to describe the three ways that God reveals Himself to us. In a very small way we also reveal ourselves variously. I am Marlene, the child of God. One facet of me is spiritual, one physical and one intellectual. All of these express as wife, mother, grandmother, friend, leader, follower, creator of various things, etc. All the while, I am Marlene, the child of God. It is my hope and my goal to reveal the child of God essence in all of the ways I express. God reveals Himself in all the ways He expresses. He, of course, is totally congruent, always true to Himself and His Nature. I, as a human, am not able yet to be that fully congruent, although I try.
Just as the triune nature of being human (spirit, mind & body) expresses in many ways, I think the Triune Nature of God expresses in all we see and beyond.
First there is God, the Divine Parent, the Creator, the One. This is God of Power. This is God of Creativity. This is the One, the only God. This is the Originator of all that is. This is the Love that permeates creation.
Then there is God the Son. God reveals Himself through this personal view of Him here on earth. God participates in human life, has compassion for us, understands us thoroughly and cares for us. God the Son has a personal relationship with us. Simply by turning to Him, He turns to us and is with us in an intimate way. God the Son is not limited to the historical Jesus. You may recall that the Bible tells us that after the resurrection, Jesus was different. Those closest to Him didn't even recognize Him. This more Cosmic Christ (beyond the body) is alive and available this very moment to be part of our everyday, every moment of life.
Then there is God the Holy Spirit, the Comforter that Jesus told us would come. The Holy Spirit inspires us, urges us onward, counsels us, guides us, is always available, always present.
All three aspects of the Trinity lead to each other, for they are all part of the One Nature of God.
This is important to me because I have a personal relationship with God as Father, as Son and as Holy Spirit. Words are incredibly limited, so I cannot reduce my relationship to words, but I am endeavoring to point to it anyway.
If you are reading these words, I'd really like it if you shared some of your thoughts on the Trinity.
Dear God, I come to You this day, as every day, to welcome You into my walk on earth. Open me more each moment to You. Wash away the darkness I may have accumulated so that Your Light may shine more fully through me. Help me understand You and our shared life. Lead me to more deeply understand Your Triune Nature. Guide my words so that I may more effectively communicate to others. Again, Your Will Be Done, Now & Forevermore. In the name of Jesus I seal this with the ancient seal of faith, Amen, Amen & Amen.