'The [school] caretaker is well' is an English equivalent of 'Il bidello a scuola va bene'. In other situations, the Italian word 'bidello' may be translated as 'janitor' or 'usher'. But no matter the context, the word is pronounced 'bee-DEHL-loh'.
Abbastanza bene in Italian means "quite well" in English.
Stai bene con i baffi? in Italian is "You're fine with mustaches?" in English.
You don't. Mangia bene is Italian. In English you say "eat well."
"Okay!" in English means Va bene! in Italian.
"I am well" in English means Sto bene in Italian.
"Good! How are you?" in English is Bene! Come stai? in Italian.
"You are fine!" in English means Tu stai bene! in Italian.
va bene?
"Hope you slept well!" in English is Spero che tu abbia dormito bene! in Italian.
"O.K., brother!" in English is Va bene, fratello! in Italian.
"Very well!" in English means Molto bene! in Italian.
"Will do!" in English is Io lo farò! ("I will do it!") or Va bene! ("That will do!" or "It's ok!") in Italian.