"La mujer duerme en el dormitorio."
Translation:The woman sleeps in the bedroom.
It does not make sense but en la dormitorio can be on the bedroom...en is also "on"
Not everything in a language can be translated literally and so you must figure out which words fit into the sentence in this case "en" is used as in and not on because one usually doesn't sleep on top of a bedroom. Hope it helps :)