"We drink tea."
Translation:Noi beviamo il tè.
Because "noi beviamo un tè" is " we drink A tea" versus "noi beviamo il tè" is "we drink THE tea" or "we drink tea". Noi beviamo tè is also accetable and probably more common than puting the il and la in front of every noun. Only put il and la when necessary, ex: "La ragazza è dolce" you cant say "ragazza è dolce" thats saying "girl is sweet" so it wouldnt make sense but saying "noi beviamo tè" or "noi beviamo il tè" is okay because both sentences make sense either way. Im learning italian too so idk if everything I said it on point but for the most part this is how im interperting it to be. Hoped I helped out.. ciao bella :)
It's preference. Some use it, and some don't. It may be more prevalent one way or the other depending on where you go, but as far as I know, formality is not involved. However if you're using 3rd person singular, leaving off lui or lei could make the subject unclear