"The boy is happy."
In case anyone was wondering: שמח is pronounced sa-me-ach in stead of sa-me-cha due to a rule refered to as Furtive Patach which dictates that a Patach (_) (the 'a' sound) is pronounced BEFORE its associated consonant IF that consonant is either Chet (ח), Hey (ה) or Ayin (ע) AND is the last consonant in its word.
Thank you, that was very much irritating me until I found this explanation!
Interesting that הבחור שמח doesn't also count. I guess I'm thinking too Yeshivish, but I've also lived in Israel and am pretty sure that'd mean the same thing in modern Israeli Hebrew, no?
That translates to "the boy he is happy" - the הוא you have there isn't necessary because we already know you're talking about a boy. (at least that's what I think!)