throne

Definition:

A throne is a specially-designed chair where a king sits to decide important matters and to listen to requests from his people.

A throne is also a symbol of the authority and power that a king has.
The word "throne" is often used figuratively to refer to the king, his reign, or his power. (See: :en:ta:vol2:translate:figs_metonymy)
In the Bible, God is often portrayed as a king who sits on his throne. Jesus is described as sitting on a throne at the right hand of God the Father.
Jesus said that heaven is God's throne. One way to translate this could be, "where God reigns as king."