i estimated the values of a variable by using AR model and after etimation of the coefficients, i made the forecasting of the sereis for out of the sample period.

the graph has three lines. one is for the forecasted values(blue colour) and other two lines are which are in red colour are for +/-2SE.

I could not understand what are those two red colour lines for +/- 2SE.

please help me in interpreting the entire graph

i am attaching the file

thanks in advance