Everything on this page lives at Stream settings.
Title and Description appear on your channel page - use them to give people a rundown on rules, links to your other sites, things like that. Tags let you give people an idea of what you typically are working on.
Adult marks the stream as adult content. New streams start with it already checked, so untick it if your stream is not adult content.
Stream URL is the ingest address, in the form rtmp://<server>/live. The
picker defaults to the server most people should use; pick a closer one if you
have a very good reason to.
Your Streamkey authenticates you to that server. It is masked until you press the eye button, and there are buttons to copy it and to generate a new one. Treat it like a password: anyone who has it can stream as you. If it leaks, generate a new one.
The Privacy section is premium only. Without premium the controls are visible but disabled, and your stream behaves as a listed public stream.
List my stream publicly controls whether you appear in the stream list while live. Turning it off only removes you from the listing: anyone with the link can still watch.
Password protect my stream does protect it. With it on, viewers need the password to see the stream or its chat, and two more fields appear:
A Direct URL is shown underneath. The password is part of that link, so anyone who has it gets straight in without being asked. Share it only with people you would give the password to.
Send an email to my followers when my stream goes live and Send Piczel.tv notifications when I go live are separate switches, so you can announce on site without sending mail or vice versa.