What is meant by this description of a type of person in the suttas?
Can anyone please give a simple explanation or some reference to other translation or commentaries?

The sutta is describing four ways to practice:


"practice that is pleasant in the present but yields pain in the future" -- seeing no harm in sensual pleasures
"practice that is painful in the present and yields pain in the future" -- an ascetic life, which is "devoted to the practice of tormenting &amp; afflicting the body"
"practice that is painful in the present but yields pleasure in the future" -- someone who is passionate/aversive/deluded and consequently experiences grief (in the present), yet lives the holy life
"practice that is pleasant in the present and yields pleasure in the future" -- someone who is not passionate/aversive/deluded, who is equanimous, withdrawn from sensuality, entering the four jhanas


What you quoted in the OP is a list of various (several) ascetic practices. I presume these were actual (current/contemporary) behaviour practiced by some people at the time.

There's a bit about Ascetism in Indian religions on Wikipedia.

Siddhārtha Gautama tried to practice austerities himself, but found it unhelpful; e.g. MN 36 describes many types of austerities he practiced, which end with his thinking:


  But with this racking practice of austerities I haven't attained any superior human state, any distinction in knowledge or vision worthy of the noble ones. Could there be another path to Awakening?'


That "other path" is the Middle Way which he tells to his five (former) companions when he meets them again after his enlightenment.

So the details are not important, just the fact that one tortures oneself?

They were presumably actual practices, which the sutta is listing as explicitly austere (unnecessary).

See also Dhutanga practices which are optional (regarding which this commentary says these are not extreme, and may optionally be adopted to further simplify a monk's life).

I'm not sure what the motive is or was for asceticism; I could guess (e.g. ascetism is also associated with devotees of Shiva), but with the Buddha stating that asceticism is fruitless (or, more specifically, is painful in the present and leads to hell in the future) I don't see much point in pursuing that topic.