Abstract and concret objects

Hello

I have a little question:
According to the definition of Wikipedia, an abstract object is, for example, justice, which can be deduced from a concret object.
https://en.wikipedia.org/wiki/Abstract_and_concrete
Will the abstract object be the action?
Eg. concret - sleeping person, abstract - sleeping? or concret - Tom eat chocolate, abstract - eating?
Concret - small house, abstract - littleness?

It is a good understanding of abstract and concret objects?