Why can we not use czysty here? Is it because tutaj is an adverb, so czysty has to be in its "adverb" form that is czysto? Wouldn't "Tutaj to czyste" be right too?
I woud say that "tutaj" and "czysto" are two unrelated adverbs that happen to be in the same sentence. It in this sentence is the same it as in it's raining. This kind of sentence needs adverb in Polish.
You cannot use "to" with adjective. If the it is a specific thing the sentence would be
Tutaj to/ ono jest czyste.
I disagree that you can use 'clean' as an adverb in this sentence (in English). As an adverb in English isn't it synonymous with 'completely/cleanly' e.g. "the fox jumped clean over the dog"? I don't see what action is being performed completely/cleanly in this sentence.
"it" in these kind of sentences sounds so wrong, but my english is not my primarly language so can anyone explain to me why "it" is needed here? I really appreciate it
Well, English just needs some subject, even in a sentence that is subjectless in Polish. So if there's no better option for a subject, then it's "it", I guess.
It's fine, in the sense of "Here is clean" (as opposed to wherever still needs cleaning).