There used to be an Events feature in Google+ long time back. Due to whatever reason it was removed but now it has been introduced back. The Events feature is already there in Facebook and it was being missed in Google+, especially by those whose social networking meets a primarily met by Google+ and not Facebook.
What’s a Google+ or a Facebook Event
Events, as the name suggests, are, sort of announcements. Suppose you are organising a party, a workshop or a seminar and you would like people in your network to attend. This is an Event. Your social networking platform allows you to promote your Event. The Events feature was present in Google+ when the Google social networking platform was launched but somehow, it got lost. The Google+ Events feature will be activated by January 24, 2017. As per this link, Google+ Events can only be created using the Android app — they cannot be created using the web interface.
Along with the Events feature Google will also be totally updating the look and feel of Google+.
Right now using the new layout is optional but most probably from January 24, 2017 onwards only the new version of Google+ will be available and the older version will be discarded.
So if you have an upcoming event and you would like to promote it using Google+ you should be able to do that using the events feature from January 24th 2017 onwards