Not easily because it touches so many different story dynamics and story points.
Here is an overview:
In various different articles, Melanie describes the justification process as flips and rotations, meaning that the items in a quad change position based on storyforming choices and flip (exchange position with another item in a quad) or rotate (the items collectively circle clockwise or counterclockwise one position in the quad) BEFORE the signpost order (1-2-3-4) is assigned to the items in the quad.
The base item -- the point of origin for the flips and/or rotations -- is associated with the problem/solution elements, the relationship of the MC domain to the OS domain, and several of the character and plot dynamics.
The flips and/or rotations happen at all four levels of the model in a sequence influenced by character and plot dynamics.
The flips and/or rotations are applied in two separate passes: once from the bottom up and another from the top down (or vice versa).
Complicating the matter, for all levels other that the Element level, the "children" of the items (e.g. the Elements under the Variations) may or may not move with the "parent" items -- again, this is dependent on character and story dynamics. This creates new associations between items at different levels of the structural model, which is what you can see in the Plot Sequence report.
All that explains the "what." The WHY has to do with why we justify at all.
SHORT VERSION -- WHY WE JUSTIFY
Human minds are natural pattern matching 'machines'. Our minds hate unresolved inequities -- imbalances created by unresolved potentials. When our mind receives an unfamiliar or incomplete pattern, especially one that creates an inequity, it must do one of two things: Identify the pattern through problem solving (the resolution of iniquities), or hide the inequity through justification, the process of creating blinders to block the inequity from awareness.
When we cannot resolve an inequity, we turn to justification. Justification hides the inequity by altering the pattern (flips and/or rotations). Difficult inequities may require multiple levels of justification (flips and/or rotations). There is a maximum of four levels of justification that still allow direct awareness of the original inequity. At any time, the levels of justification may be dismantled and the inequity addressed directly through problem solving. However, if a fifth level of justification is applied, the energies needed to maintain the levels of justification collapse the inequity into a blind spot -- a semi-permanent, self-sustaining mental black hole. At that point, direct observation of the inequity becomes virtually impossible from the inside (full justification). In most cases, it requires external pressure (in the form of an Influence character) to tear down the levels of justification (directly related to the signposts) before the core inequity is once again visible to the mind.
The benefit of blindness to inequities is that one may ignore unresolvable inequities, big or small. The downside of this blindness is that circumstances may change and one's response to the initial stimulus may no longer be appropriate. For example, you may not be able to cure a sickness, so hiding the sickness from oneself and treating the symptoms may be sufficient for a time. However, if the sickness worsens or metastasizes into something lethal, being blind to it no longer serves its purpose and may be fatal unless the blind spot is dismantled in time to cure the disease.