vs
QUICK ANSWER
"Of" is a preposition which is often translated as "de", and "month" is a noun which is often translated as "el mes". Learn more about the difference between "of" and "month" below.
of()
A preposition is a word that indicates the relationship between a noun and another word (e.g., He ran through the door.).
month()
A noun is a word referring to a person, animal, place, thing, feeling, or idea (e.g., man, dog, house).
