it's hellish here?
Hellish = infernal(e), infernaux, infernales
enfer → is a noun where as "hellish" is an adjective.
Yes, but who actually says "it is hell here"?
Quite a number of English sentences in this course - even though grammatically correct - are not something anybody would ever say in actual conversation or even in writing.
"It is Hell here." This is such a useful phrase. I have this sign posted at work. Now I can post it in French! "C'est l'enfer ici!"