The "mean" is the median location between the erratic, back and forth, "true" (current) locations which vary at most by about 2° orb.
BLM is at one end of the center-line of the Moon's elliptical orbit, where it's at "apogee", furthest from the Earth. The back and forth of the "true" position, relative to the always direct, median "mean" position, is called "nutation", or "oscillation".
Same with the Lunar Nodes, where the Moon's orbital path intersects with the zodiacal Earth/Sun orbital plane. The mean Nodes are always retrograde, but the changing true positions can cause current, periodic, direct movement.