The meaning would be different and we would rather say "tu es un garçon généreux", "tu as bon coeur" or the like.
Note by the way that "un homme bon" or "une femme bonne" are correct but for other reasons:
- un bon homme would be confused with "un bonhomme" (= a figure, a little man)
- une bonne femme is derogatory and means "old biddy".
Can I leave out the 's' in 'es' and pronounce as Tu e(s) un bon garcon?
Is "bon" used only for moral goodness, or can it also br used for being good at something?
"bon" can be used to mean good at stg, but the stg is usually explicit:
- he is good at maths = il est bon en maths
Lordy, I have repeateslu listened to this sentence and have difficulty hearing the un..unless I play the slow version.