Question

Non luminous object do not emit any light of their own. How is it still possible that we are able to see them

Answer 1

The above answer is the best and proper explanation.
I have attached two images for better understanding.

Example 1:

Book is non-luminous. But it reflect light from bulb so that we see the book.

Example 2:

To percieve something, the object of interest have to be able to reflect light into our eyes. If this object lack the ability to transmit light, then we cannot see it. A famous example of this are black holes