One God, Three Persons. It’s how we describe the relationship between the Father, the Son, and the Holy Spirit. It’s a complete unity of being - with nonetheless separate (but not separated) persons – grounded in Love.
The persons of the Trinity show us the Love that made us. And the Love that saves us. And the Love that remains with us. And that each is the same One who Loves us.
Which is why the Trinity sometimes gets called a “mystery.” Not because it’s made up or needlessly complicated. But because there’s more to it than we can never fully unpack, and so much more that’s worth unpacking.
And it’s in that unpacking – thinking about it, praying about it – that we can start to see the place for each of us in the Love of God. The Love that looked at creation and said “I know what this needs, you.”