Ven. Sujato translates it, "a person in training" (which makes sense in the context).
18.104.22.168 What is purisa? The usual translation for purisa is “person,” usually a “man.” And the usual
word for “individual” is purisa,puggala or simply puggala, as if famously used in reference to “the pairs of
persons, the 8 individuals” (purisa,yugāni aṭṭha,purisa.puggalā) in the recollection of the noble community (saṅghânussati).
Here, purisa refers to a “person,” which loosely refers to a being with some capacity for thought and
will (in the sense of personal action).
The Buddha has tamed animal persons (tiracchāna,purisa), such as the naga-rajah Apalāla, Cūḷodara, Mahodara, Aggi,sikha, Dhūma,sikha, the naga-rajah Āravāla, and the elephant Dhana,pālaka.
He has tamed human persons (manussa,purisa), such as the young nirgrantha Saccaka, the brahmin
youth Ambaṭṭha, Pokkhara,sāti, Soṇa,daṇa, and Kūṭa,danta.
He has tamed non-human persons (amanussa,purisa), such as the yakshas Āḷavaka, Sūci,loma and
Khara,loma, and Sakra, the lord of the devas.
22.214.171.124 What is damma? The word damma (Skt damya)
is an adjective, the gerundive of dameti
(causative: Skt dāmyati), “to bring into the house, to domesticate; to tame, convert; to be restrained;
especially with reference to tamable animals; figuratively, to humans to be tamed or converted.” Technically, damma means “to be tamed, or should be tamed,” but the context here clearly refers to the
capacity or readiness of a being or person for taming—hence, “tamable.”
“Tamable persons” (purisa,damma), that is, those to be trained, according to the Sutta are of 4 kinds:
(1) those who are trained with gentleness; [126.96.36.199]
(2) those who are trained with harshness; [188.8.131.52]
(3) those who are trained both ways (with gentleness and with harshness); [184.108.40.206] and
(4) those who cannot be trained at all: the untamable. [1.3.5]