New Earth also called EARTH-0 is the current main universe.
You'll find the list of all the Earths and domains of the gods in the map of current multiverse here
The current Multiverse is the evolution of previous Multiverse.
The first Multiverse had an infinite number of Earth.
That ended with Crisis of Infinite Earths where they made that there's only one Earth.
Then they brought the Multiverse concept back.