The temple being measured is the human body, and this porch is its threshold, the entryway of consciousness where a person first crosses from the outer life toward the inner sanctuary. Every dimension given is a weighing of the finished form of the body against what it is built to hold. The steps mean that the way in is not flat but graded: awareness climbs by degrees, rising through levels rather than arriving all at once.
The 2 pillars standing on either side are the paired columns of energy that rise along the spine and support the whole structure, the balance of the 2 sides through which the ascent is even made possible.
Porch: the threshold of the body-temple, the vestibule of consciousness where the outer life is left and the inward turn begins
Steps: the graded degrees by which awareness climbs, rising through levels rather than reaching the height at once
Pillars: the 2 columns of energy that rise along the spine and hold the body upright, the balanced left and right that let the ascent take place
20 cubits: the doubled fullness of the senses, the outward measure of the form that must be passed through
11 cubits: the number just beyond the completion of 10, the point of crossing over from one order into the next