Thanks for the suggestion. But I return the question, asking what specifically is missing. Because:
* multipole moments (of which mono-, di- and quadrupole moments are the lowest order examples) are discussed in the video of the ‘multipole moment’ section. The hint for the task that comes with that video has more explanations for someone who is less familiar with it. And the optional background text has extra info as well.
* What parity is, is defined at the beginning of the video on ‘why nuclear electric dipole moments are zero’.
The intended effect was that even someone who did not meet these concepts before, should have acquired an impression about multipoles and parity when he/she arrives at the present video. If that turns out not to be the case, then please try to explain more precisely what is missing and where it should best be provided.