When aligning the lines of convergence on the right side of the corner, which vanishing point do you use?

Before we get into this, I want to make one thing very clear: the lesson content ... lines that are parallel to one another will ultimately converge towards - you guessed it - a vanishing point. ... A scene will be governed by any number of vanishing points. ... If your view is aligned mostly to a box's corner, use 3 point perspective.

Explanation:

what does that mean

answer; isometric perspective;