The Trinity is the biblical truth that there is one God who exists eternally in three distinct Person: the Father, the Son (Jesus Christ), and the Holy Spirit. These three are not three gods but one God, equal in nature, power, and glory (Matthew 28:19; 2 Corinthians 13:14).
Each Person of the Trinity has a distinct role. The Father plans salvation, the Son accomplishes it through His death and resurrection, and the Holy Spirit applies it in the lives of believers.
Although the Trinity is beyond full human understanding, it is clearly taught throughout Scripture and is a foundational doctrine of the Christian faith.
One thing that should be clear is that God is one, but functions differently in three different dimensions, the Father, the Son and the Holy Spirit. The same way we are made of one person but body, soul and spirit.