The 'city of Judah,' as in Isaiah 40:9, signifies the doctrine of love towards the Lord and love towards our neighbor.

(Reference: Apocalypse Explained 850)

A 'month,' as in Genesis 29, signifies the end of an earlier state and the beginning of a following state, thus a new state. 'A month' signifies a full state.

(Reference: Arcana Coelestia 3814)