The Pual stem represents intensive action in the passive voice (as opposed to the piel which is intensive action in the active voice).  See more here or this video.

The fundamental idea of Piel [and the Pual], to which all the various shades of meaning in this conjugation may be referred, is to busy oneself eagerly with the action indicated by the stem. This intensifying of the idea of the stem, which is outwardly expressed by the strengthening of the second radical, appears in individual cases as

(a) a strengthening and repetition of the action;

(b) a causative sense (like Hifil);

(c) Denominatives are frequently formed in this conjugation. (source)

Translating the pual.

The Verb Chart:
Qal Stem Simple action active voice
Nifal Stem Simple action passive voice
Piel Stem Intensive action active voice
Pual Stem Intensive action passive voice
Hifil Stem Causal action active voice
Hofal Stem Causal action passive voice
Hitpael Stem Intensive action reflexive voice