It is a period of time following the birth of the Church in which the Gospel of the Kingdom is to be preached so that people come to God through Faith in Christ Jesus.   

At the word Finished Christ Jesus became King of Kings and Lord of Lords and the Earth became part of the Kingdom of Heaven in terms of property.   

At the End Of The Age Christ will Return to establish a new age/dispensation - the Millennial Kingdom age.   This age will last for 1000 years.   

At the end of Millennial Kingdom age there will be the final Resurrection of all the Dead followed by the White Throne Judgment.   

Death and Hell will then be cast into the Lake Of Fire and God will create a New Heaven and a New Earth.   

As far as the Biblical prophecy goes, the New Heavend And Earth age is the final age.