Declination and distance can be compared with the geocentric values, the small shift is due to the difference of the location in space of the observer in Edinburgh compared to the centre of the Earth. Pluto V is the visual magnitude. This changes with distance from the Sun, from the Earth, and with the angular distance of Earth and Sun as seen from the planet. El is the elongation, i.e. the angular distance of the planet from the Sun. This is listed positive for eastern elongation, where the planet lags behind the Sun in their daily motion across the sky.
L is the fraction of the disk that is illuminated.
1.0 is e.g. full moon, 0.0 new moon. This is negative if its south pole is inclined towards us. PA is the position angle of the planets rotation axis. CM is the central meridian. The planets have a system of planetocentric longitude similar to geographic longitude on the Earth.