I just signed up, but I don't really get what it is? Is it just some kind of
folder sharing thing? or is that just a part of it? I see it has a chat..
It's a system for making PGP/GPG easier for the most part -- which includes secure file sharing, chat, and so on. One of the key components is proofs of identity: You can proove that you own various accounts that say you're who you say you are -- each adding to the trust.
You can also easily send/recv encrypted messages without so much cryptic stuf
TL;DR: It's crypto for the masses.
--- ENiGMA 1/2 v0.0.6-alpha (linux; x64; 6.10.3)
* Origin: Xibalba -+- xibalba.l33t.codes:44510 (21:1/121)