I played on a wL server last night, I went to bed and now I can't join any wL server : Please explain it to me :p

I played on a wL server last night, I went to bed and now I can't join any wL server : Please explain it to me :p

ahhhh... I see the Reason: left live pug w/out sub (1)
what is "sub"? someone tell me

and what is live pug :p i'm newbie

I don't think I'm the best to explain it since I'm horrible at explaining stuff normally lol but a live pug just means there is a 5v5 going on at that moment and a sub just means somebody in spectate who is waiting for somebody to leave or something to take their spot so when you left a live pug with out a sub just means that you left that match without anybody there to take your spot. Hope I was able to help you understand