This column reflects the "nice" setting of each process. A process's nice is inhereted from its parent. Most user processes run at a nice of 0, indicating normal priority. Users have the option of starting a process with a positive nice value to allow the system to reduce the priority given to that process. This is normally done for long-running cpu-bound jobs to keep them from interfering with interactive processes. The Unix command "nice" controls setting this value. Only root can set a nice value lower than the current value. Nice values can be negative. On most systems they range from -20 to 20.
The nice value influences the priority value calculated by the Unix scheduler.