Reset is a term used in the community which is synonymous with both "round of gameplay" and "the end of the round of gameplay".
For example one could say "This is my third round playing Earth Empires" or "This is my third reset playing Earth Empires."
For the other meaning one might say "The round ends in three days" or "The reset is in three days."
The first example of usage is the most common.
This term comes from the fact that the database for a server was "re-set" or emptied at the end of the round in Earth:2025. This is no longer the case in Earth Empires, and all country data is stored indefinitely.