The word Trinity is one the church developed to summarize the Bible’s teaching about the nature of God. It comprises two words: “tri” – meaning three, and “unity” – meaning one. The Bible teaches that there is one God who always exists in three persons, known as the Father, the Son, and the Holy Spirit. These are not three names for God, nor are they three alternate ways he might manifest himself on different occasions. They are three distinct persons who co-exist, interact, and perform different roles. For example. it is the Father who oversees all things, it was the Son who took a human nature and lived amongst us as Jesus, and it is the Spirit who is now active throughout the world. Yet each are truly, fully, and equally the one God.
It should be no surprise that there are things about God that our finite minds cannot fully comprehend. How he can be both one and three is surely one of those things. Nevertheless, it is important that we comprehend that this is what he is.(Matthew 28:19, John 5:16-30, 14:15-21)