What is holiness?

See also here: https://mikyab.net/posts/75964

The Torah calls a monk holy. What does that mean?
You defined holiness as being where there is more inspiration of the Divine Presence. A. What is the inspiration of the Divine Presence? B. Is there value in being in a place where the Divine Presence resides?

I sent a link. The borrowed use of this title is explained there.
You are asking about concepts that are difficult to define. It is about a place and time where God is more present, and it is likely that being there also improves our own situation.

What does it mean that he is more present where he belongs, the reality of a place?
And if it ‘improves’ our reality, does it also have value or is it only materially better for us?

I see no point in this strange discussion. Yes, it is true that he is more present in some place, or appears more there. He is more present in the temple than in the fields or in the filthy entrances (I leave this to the Hasidim). The improvement does not seem to me to be material, nor is there any reason to suppose that it is material. It is a closeness to God.
I think I am done here.

It is possible that the monk is called holy because his hair becomes a holy object belonging to the sacrificial service (it is burned under the brazier of peace offerings). Similarly, the priests are called holy because their hands and feet are holy objects in the Temple (they purify them before the service).