I think he means Solo PvE or PvP, or Team PvE or PvP.
I enjoy playing with a team. The problem is I have a hard time finding a team to my liking. Good teams will help each other out in ways not directly in combat. In other words, like this last GE, there was a commendation called Contaminated. It pretty much sucked. But, with one person there as a dedicated Reclaimer, it was easier. Even after helping numerous teams with people running Dragon's Nest (with my much stronger account, not the account that also needed those runs)repeatedly so they could get their various commendations such as pistol only, they didn't want to help me on my last account though they said they'd help. One did for about 10 minutes. All in all, I ran DN probably 6 times with this person. Meh, reminded me why I generally go solo anyway..
So, I did what every self-respecting person with 3 accounts and extra computers (set up for gaming) does. I joined the other characters session. I could run in, drop my support station and then run in with the second account and do all the killing. I could certainly still die and even wipe, but it was a lot more fun than dying all the time. Even with doing that, at 150 out of 300 done. I figured if I kept going I was going to lose my sanity. I'd like to know who's %@$@% bright idea it was to set the bar at 300. The point of that GE was to keep your distance and take headshots. But for some reason, we are to run in close and get contaminated just for this...