They are three persons in one essence. I don't think it is possible for us to ever understand how that works because in our worls and the way our minds and earthly nature operate, we cannot fathom a triune God. My kids have
This Book that explains the trinity like the three parts of an apple: The seeds, the fruit, and the skin. All distinct and seperate things, yet all apple. Its a really good book for the kids. You should check it out.