The trinity is basically the reason why Muslims are not Christians. They don't understand it. But I heard this explanation online on YouTube on the Trinity.
Here is how it goes:
Since God is omnipotent, He can be at multiple places at once. And He can be in multiple forms at once, at the same time.
That is what I remember from the explanation.
Here is my version, though it might sound more "philosophical":
The Godhead is made of three components. All are equal, and God cannot be without each of them. Three distinct persons, but they all make up God, or the Godhead, and they cannot be complete without each other all together.
My theory is not complete yet, but that is what I think.
How would you explain the Trinity?