g+ meaning in Messaging ?

Google+ (pronounced and sometimes written as Google Plus; sometimes called G+) was a social network owned and operated by Google. The network was launched on June 28, 2011, in an attempt to challenge other social networks, linking other Google products like Google Drive, Blogger and YouTube. The service, Google's fourth foray into social networking, experienced strong growth in its initial years, although usage statistics varied, depending on how the service was defined. Three Google executives oversaw the service, which underwent substantial changes that led to a redesign in November 2015.

Due to low user engagement and disclosed software design flaws that potentially allowed outside developers access to personal information of its users, the Google+ developer API was discontinued on March 7, 2019, and Google+ was shut down for business and personal use on April 2, 2019. Google+ continued to be available as "Google+ for G Suite"; all users transitioned to "Google Currents" later.