What is God? How do you define or explain what He is?

As westerners we want answers to those questions but the Bible does not even try to define God. All the Bible does is tell us what God said and what He did.
In Exodus 3 when God meets with Moses in the burning bush, Moses asks God “who or what are You?” and God responds with “Yhwh: I AM what I AM or I will be be what I will be.” In that Name God tells Moses, “I am beyond description and comprehension so don’t even try. I can’t be described in a word, defined by an image, or contained in a building. I am beyond you and different from you, Moses. The only way you can know Me is by the way I choose to reveal Myself. And I am going to reveal Myself in 2 ways -My Word and My actions. You will know Me, Moses, bc of what I do.”
And this God then enters into Covenant with Israel, redeems them through Egypt, personally leads them through the wilderness for 40 years, faithfully responds when His people call, sends His own Son to live among them, and consistently shows His desire to dwell among His people here on earth. 
As you read the Bible notice how God’s actions are placed front and center. What do you they tell us about God? Read His words and wrestle with what He says. What do they reveal about God?
The Bible isn’t interested in proving God, explaining Him, or even trying to understand Him. It takes all that for granted. In the Bible, we get to see God revealing Himself to us through His Words and His actions.
So, believer, this year don’t try to define or even understand this God. Just sit back and enjoy what He has done and is doing. Today we say God’s Name so lightly but we can’t even begin to grasp the God to whom this Name belongs.
He is God.
I can’t begin to describe what that means. But I can tell you this – Yhwh has been good and faithful to me and I will praise His Name.