What symbol is this?

[mohawk apple]

I've never seen this symbol before! In a newb to android lol the round symbol to the left of the wifi symbol!

 

[Aquila]

It means you have do not disturb or priority notifications turned on. Pull down your notification shade to quick settings and it'll be in the middle row on the left.

 

[QuasiHobo]

As above.. Im doing this by mistake a lot of times, which kinda bothers me.. And im not sure how it happens?