What does that mean at Fortnite? - 1

How can you change that and what does it mean? And how can I watch my friend?

please answer I'm still new.

That the lobby is closed and you can't save after

A private lobby so closed you can only invite people.

How can you unlock them?

How can you unlock them?

He has to do that

He has made his lobby private

Can't do that, everyone can do that, for example if you want to play in quiet games without someone entering the lobby.