Events is a way for you to create real-life events in your community, like dōjinshi exhibitions and general exhibits!
As long as you have a pixiv account, you can join in!
However, if you'd like to make an event yourself, you'll need a pixiv Premium account.
Within your community, you can publicize your event, gather participants, check to see what events the users you follow are attending, host exchange parties beforehand, and more!
You can check out Events from the menu in the top left of your header.