'things to be realized'.

Recollection of former states of existence is to be realized through remembrance (abhiññā 4).

The vanishing and reappearing of beings is to be realized through the divine eye (abhiññā 5).

The 8 deliverances (vimokkha) are to be realized through the mental group (kāya, here feeling, perception, mental constructions; s. kāya).

The extinction of fermentations is to be realized through insight (vipassanā).