OverTheWire Bandit Wargame Solutions 0-13 (WalkThrough)

In level 6 at the command line "find / -userbandit7 -group bandit6 -size 33c 2</dev/null" can i know what is the exact function of 2</dev/null is?

Hi, everytime I try to make the directory (mkdir) in level 12, it tells me that my permission is denied :( Do you know how I can go about dealing with this? Thanks.