The "global_frame" parameter defines what coordinate frame the costmap should run in, in this case, we'll choose the /map frame. The "robot_base_frame" parameter defines the coordinate frame the costmap should reference for the base of the robot. The "update_frequency" parameter determines the frequency, in Hz, at which the costmap will run its update loop. The "static_map" parameter determines whether or not the costmap should initialize itself based on a map served by the map_server.
The "global_frame", "robot_base_frame", "update_frequency", and "static_map" parameters are the same as described in the Global Configuration section above. The "publish_frequency" parameter determines the rate, in Hz, at which the costmap will publish visualization information. Setting the "rolling_window" parameter to true means that the costmap will remain centered around the robot as the robot moves through the world. The "width," "height," and "resolution" parameters set the width (meters), height (meters), and resolution (meters/cell) of the costmap.