There are a number of ways to describe the nature of God from a Christian perspective.
Monotheism - Christians believe that there is only one God. They are monotheists.
Trinity - most Christians believe that there are three distinct parts (usually referred to as Persons) to this one God and that these three aspects form a unity. This belief is called the doctrine of the Trinity:
God the Father - the creator and sustainer of all things.
God the Son - the incarnation of God as a human being, Jesus Christ, on Earth.
God theHoly Spirit - the aspect of God which is active in the world, drawing people towards God.
Holy - God is 'other', different from anything else - separate and sacred.
Omnipotent - God is all-powerful. Everything consistent with God's nature is possible.
Omniscient - God is all-knowing, of past, present and future.
Omnibenevolent - God is all-good.
Omnipresent - God is present everywhere.
Immanent - God is active and 'in the world' today.
Transcendent - God is also 'outside the world'. God is not active in human affairs. It is up to humans to act in the world on God's behalf.
Personal - individuals can have a personal relationship with God. The Bible often talks of God in human terms, eg as friend, king, parent, and judge.
Impersonal - many Christians think of God in impersonal terms. The Bible sometimes talks of God in this way, eg as a power, goodness, truth, justice and love.