"The house turns into a hotel."
Translation:La casa se convierte en un hotel.
I am not sure why there is a need for 'se' in this sentence. Why is it not just 'La casa convierte en un hotel' after all the house is not converting itself?
What the "se" does is that it makes the expression impersonal. There is no real subject in the English sentence either, where the house also does the "turning". In the Spanish phrase, if you leave out the se there is no ojbect and then the house would turn something, that is not specified at all, into a hotel.