Help me please ! What does "Wholesome" exactly means ??

I'm starting to see this often in yaoi : the tag "wholesome". I know "whole" sort of mean full / entire, in my language (i'm french). But even if i searched for definitions i can't find the exact and clear meaning of this word.
So can someone please explain it to me with their own words ??┗( T﹏T )┛