Translation:He will have missed the way to the gym.
It's usually used as gym (and most would understand that), but it could also mean academy (usually that is made clear by context). I hope it helps! =]
"He will have missed the way to the gym" is horrible English, if anybody wants to know. You don't miss your way. You lose your way or you get lost (on the way to somewhere).
If I want to say academy like in english wich word would be te accurate one instead of academia?
Well, if you mean academy as in the place where studying happens (such as a school) or a group/society (the Academy Awards, for instance), then the only word is really academia C: