High sec is space rated 1.0 to 0.5, 0.4 to 0.1 is lowsec and 0.0 is
high security space is nice and safe, no one can attack you unless you are in a player corp and you get a Wardec from another corp. Concord which are NPC police will most of the time kill the attacker before they kill you.
Ocacasinally people do suicide cheap high damage ships if the targets cargo is lucrative enough.
You can also still join Faction wars which is like a big Corp War but against Empires and you get some rewards.
Low Sec has no Concord but still has Gate guns which gives the attacker a dissadvantage, also no "bubbles" which pirates put down to stop you warping.
so is a bit safer than 0.0 but almost as bad and not as profitable, you don't wanna go here really.
0.0 is where corps join forces to form alliances and alliances join together to form a few major powers that do battle over solar systems. You need to join a corp that can hold its own or has protection to survive out here. Although once out there in an area with blues it is safer than low sec most of the time and has all the good money making oppertunities and the best PVP with Capital ships and 1000 ship battles.
The thing about Eve is it is all player driven so to get into the big stuff it obviously requires effort as you are playing in a sandbox with 1000s of others, some of which are very dedicated and spend all their lives in this game, but if you don't want to just join a big corp and pay your tax and leave the leadership to the others like me. I log on a few hours a week for PVP and a bit of PVE if I die too much.
And there are still a loads of other more solo content that you can do without needing anyone else and at your own speed if you wish.