Well it is important to understand the difference between a being and a person.
Being describes WHAT something is.
Person describes WHO someone is.
WHAT am I? I am a single human BEING.
WHO am I? I am [Judas Thaddeus] (don’t mind my privacy

).
WHAT is God? God is a single Divine BEING.
WHO is God? God is the Father. God is the Son. God is the Holy Spirit.
That’s one way to go about it, but here’s also a more complex explanation:
There is only ONE God.
God is the Father, the Son, & the Holy Spirit.
The Father is not the Son, the Son is not the Holy Spirit, the Holy Spirit is not the Father.
NEVERTHELESS,
The Father, the Son, & the Holy Spirit “IS” the ONE GOD.
There is ONLY One God.
I hope that helps.