The demon speaks Polish. Translation for the curious.

The poem at the beginning and end of the film is:

Original:
"Rosną sobie grzybki w trawie
I patrzą na świat ciekawie.
Co to będzie? Co to będzie?
Tyle grzybków w trawie siędzie."

English:
"Little mushrooms grow in the grass
And look upon the world curiously.
What will this be? What will this be?
So many little mushrooms sitting in the grass."

The conversation the demon has with Emily in the empty lot:

Original:
"Wyglądasz bardzo ładnie. Kim ty jesteś? (Dbają o ciebie?) Dlaczego odchodzisz od ojca? Czy mogę cię wziąć? Czy mogę mieszkać w ciebie? Ja dbam o ciebie. (I like you.)"

English:
"You look very pretty. Who are you? (Do they care about you?) Why are you walking away from father? Can I take you? Can I live in you? I care about you. (I like you.)

The text in parentheses was very hard to make out and is a bit of a guess. Yes, as far as I can hear, the demon does say, "I like you" in English. Interestingly, the demon has bad grammar! It should say, "Czy mogę mieszkać w tobie?" using the locative case, not the accusative or genitive.