There is nothing that anyone can know about God's nature unless He reveals it to humankind. Without divine revelation humanity will be in darkness. Fortunately, the Bible has told us about God's nature. From the Scripture we can discover four basic description of God's character.
1. God Is Spirit
God is a spirit being. Jesus described God in this manner.
God is spirit, and those who worship him must worship in spirit and truth (John 4:24).
God is not "a spirit" rather He is "spirit." Spirit is His nature - He is not a physical being. Because God has no physical form Israel was forbidden to make any images of Him.
You shall not make for yourself an idol, or any likeness of what is in heaven above or on the earth beneath or in the water under the earth. "You shall not worship them or serve them; for I, the Lord your God, am a jealous God, visiting the iniquity of the fathers on the children, on the third and the fourth generations of those who hate me, but showing lovingkindness to thousands, to those who love me and keep my commandments" (Exodus 20:4-6).
2. God Is Light
The Bible also says that God is light.
This is the message we have heard from him and announce to you, that God is Light, and in him there is no darkness at all (1 John 1:5).
This can refer to the glory and majesty of God. Notice the Bible does not say that God has light; He is light. The Bible says that.
Which he will bring about at the proper time - he who is the blessed and only Sovereign, the King of kings and Lord of lords, who alone possesses immortality and dwells in unapproachable light, whom no man has seen or can see. To him be honor and eternal dominion! Amen (1 Timothy 6:15,16).
3. God Is Love
The Bible says that God is love.
We have come to know and have believed the love which God has for us. God is love, and the one who abides in love abides in God, and God abides in him (1 John 4:16).
Love involves other attributes of God including grace, kindness, and mercy.
4. God Is A Consuming Fire
The Bible also describes God as a consuming fire.
For our God is a consuming fire (Hebrews 12:29).
Read about fire being a symbol of God here https://www.blueletterbible.org/faq/don_stewart/don_stewart_281.cfm
Summary
The Bible does not attempt to prove God exists or give any definition of God. Yet it does describe His nature in four ways: God is spirit - His nature is not flesh and blood. God is also light - there is no darkness in Him at all. God is also love. Finally, God's nature can be compared to a consuming fire. These four descriptions provide some insights into God's nature and character rather than giving us a definition of Him.
Taken fromhttps://www.blueletterbible.org/faq/don_stewart/don_stewart_281.cfm