Fauces, n.pl. [L.]
1. (Anat.) The narrow passage from the mouth to the pharynx, situated between the soft palate and the base of the tongue; -- called also the isthmus of the fauces. On either side of the passage two membranous folds, called the pillars of the fauces, inclose the tonsils.
So the pillars of the fauces are the uprights on either side of the entrance to the throat.
Now you know.