He just said, open a console, then go to the directory where your executable file should be, then run it.
mean change directory and is the name of the command which allow this.
mean that you'll need to tell the system that the file you want to run is the one in the "." directory, so the directory where you are actually.
By example, if your project is directly in your home directory, just type
cd ~/project_folder/bin/debug/
./exefile
. (The ~ is a shortcut to your home directory.)