Hi Josipa,
Josipa said:
Have a question about the letters on the pillars on the High Priestess card.
What do they stand for?
As Rosanne noted, B stands for Boaz and J for Jachin. These are Hebrew words from the Biblical account of Solomon's Temple, recounted in I Kings 7: 15-22 and 2 Chronicles 3: 15-17. The two names mean -
Boaz - He comes with power.
Jachin - God establishes.
The two pillars are important symbols in freemasonry, in the symbolism of which Waite was an expert. See for example
http://www.freemasons-freemasonry.com/larsonwilliam.html
(and type in +jachin +boaz +temple +masonic +waite +tarot in Google for countless others)
See also Bob O'Neill's sources of the Waite-Smith images
http://www.tarotpassages.com/old_moonstruck/oneill/2.htm
The account in 1 Kings 7:21 reads : "He set up the pillars in the porch of the temple; and he set up the right pillar, and called the name thereof Jachin; and he set up the left pillar, and called the name thereof Boaz." (King James Version)