We do not know what the Creator is because we ourselves cannot define Him. We can only define something relative to our feelings.

Therefore we call Him the Creator because we begin to become aware and define Him only from the state when He gives birth to us and defines Himself as our Creator, only from this moment but not before.

We differentiate these states into one that is not given to us in sensations, Atzmuto, which means existing by Himself, and the state when we begin to feel Him, that is, we give Him some of our own definitions, designations, and descriptions. And these descriptions, i.e., what enters into my properties that I can work with, I can remember and pass on to others.

From what we know and can determine, we can say that the Creator has created one soul in His likeness, meaning equal to Him but opposite of Him. Therefore, we can talk about it as “creation.”

Creation is that which is not in the Creator. In itself, this is an incomprehensible action, but it is precisely what is called creation. And the one who performs this action is called the Creator.
[332395]
From the Daily Kabbalah Lesson 2/24/20, “Preparation for the Convention”

Related Material:
Atzmuto and Boreh
Kabbalistic Terms: “Atzmuto”
The Creator And Atzmuto