In Google Analytics, “Users” refers to unique visitors. “Users” show up on the default Google Analytics dashboard as soon as you log in to the tool. Any time new visitors land on your website, Google Analytics assigns them a unique ID—or client ID—that’s stored as a cookie in their browsers. Special measures are taken by Google's analytical programs or others to filter out visits that are not human, such as visits from spiders, crawlers and other bots.
The official Google Analytics definition of this term is: “Unique Visitors are the number of unduplicated (counted only once) visitors to your website over the course of a specified time period.” However each user counts as one so, if the same IP address accesses the page/site these visits all count as one.