a) This form primarily expresses a "reflexive" action of Qal or Piel
See for Qal H8851
See for Piel H8840
he wore he dressed himself
he washed he washed himself
he fell he flung himself, he fell upon, he attacked
he sold he sold himself, he devoted himself
b) It expresses a reciprocal action.
they saw they looked upon one another
they whispered they whispered one to another
c) Some verbs in Hithpael are translated as a simple action. The
reflexive action os understood.
he prayed, he mourned, he became angry
This form accounts for 1.4% of the verbs parsed.