"They sleep in a hotel."
Translation:Elas dormem em um hotel.
No= em+o (masculine - at/ in the), na = em+a (feminine - at/in the). Plural: nos/nas. Num= em+um (masculine - at/in a), numa= em+uma (feminine - at/in a). Plural: nuns, numas. (Plural is used when talking. When writing it's better to use em uns, em umas). Use them as you'd use in English. Sometimes em/no(s), em/na(s) are interchangeable.
I think I understand that an m or n before a consonant or at the end of a word makes the previous vowel nasal. However, in a sentence such as the one above, do you still pronounce the vowel nasally because there is a vowel that begins the next word? Do you pronounce the m at all as a buffer between words?