Dis·cern verb di-ˈsərn, -ˈzərn
The word to discern means; to come to know, recognize, or understand (something)

Full Definition of the word “DISCERN”

a : to detect with the eyes <discerned a figure approaching through the fog>
b : to detect with senses….

To do a research, to rationalize a thing or to do a feasibility study concerning a certain matter, which leads to the understanding of that matter.
2
: To recognize or identify as separate and distinct :<discern right from wrong> 
To understand the hidden motive, agenda or subliminal message concealed in a thing or darkness.

The moral ability which is gained via the art or practice of separating the holy things from the unholy things, the clean from the unclean.
3
: to come to know or recognize mentally <due to lack of discernment he was unable to discern his motives>
intransitive verb
: to see or understand the difference