From the title, I had a question and found the answer in the FAQ:

What’s an unconference?

An unconference is a conference in which the participants – rather than the organizers – decide which sessions happen each day and on which topics. In the many years we have been organizing unconferences, we have found that for complex subjects like the Fediverse, attendees get more value (and fun!) out of unconferences than from traditional conferences. Sounds disorganized? It did to us, too, until we actually experienced our first one. So don’t worry, it will be fine :-)

Here are some suggestions for how to prepare for an unconference.