Graphs for historical and smoothed variables

I am estimating a DSGE model using Dynare. I got the graph for Historical and smoothed variables. Most variables have only black lines. One of the variable has 2 lines, one is red and the other is black. What is the red line mean? And in the graph for smoothed shocks, one shock has no fluctuations at all, there is only one black straight line stay at level 0. What’s the meaning?