Can Someone interpret this function for me?

http://prntscr.com/hlfm2

im confused on +/- thing

it appears to me that you can tell it to either stop close to before or after the number you chose in case it can't stop at your desired amount

i cant understand it because its a newly updates function

dont know whats +/-0

it means plus or minus = if you want 100 you might wind up with 90 or 110 if you give it a range of +/- 10

makes it more random which is nice

Yes, also it is explained on the hint (hold mouse over it).

thanks