"It is too late for breakfast."
Translation:Jest za późno na śniadanie.
Well, not necessarily, I can without a problem imagine using it for feelings and emotions, as it implies "This feeling that you feel/That emotion that we discuss"... The examples when it will be only "jest" and not "to jest" are probably quite rare.
I think that if the English sentence starts with "This is", there's probably no way that it will be one of those exceptions, but this one starts with a completely impersonal "It is". Such exceptions will probably denote something about time, weather, sometimes the way you feel. At least that's what comes to my mind right now.
Jest za wcześnie by pić. = It is too early to drink.
Na plaży jest gorąco. = It is hot at the beach. (It could be "Jest gorąco na plaży" as well - although a bit less natural, and I don't think that "at the beach" can be treated as a subject, so there's none)
Jest mi niedobrze. = I feel 'not-good' = I feel sick = I feel like I'm gonna vomit.