God is a Person. In fact, God is three Persons in One! This is the doctrine of the Trinity. God has one essence, the stuff that makes Him God. However, this essence appears to mankind in three Persons -- God the Father; God the Son, that is Jesus; and God the Holy Spirit.
In attempting to understand how the Bible describes God, we often speak of His attributes. These are the characteristics that explain God to mankind. His attributes include things like love, goodness, and peace. To some extent God shares these types of attributes with mankind. Some call these His moral or communicable attributes.
God is also all-powerful, all-present, and all-knowing. He has some attributes that He does not share with mankind. These are truly the traits which make the Trinity the true God.
In order to better understand God, one must understand all of His attributes.