This is the 144th most frequent German word.
september
"September" in German is the same as in English: the ninth month of the year.
In this sentence, 'September' is used as a noun to name the ninth month of the year.
Der September ist mein Lieblingsmonat.
September is my favorite month.
Here, 'September' is used in the prepositional phrase 'im September', indicating the time when something happens.
Im September beginnt der Herbst in Deutschland.
In September, autumn begins in Germany.
In this instance, 'September' is addressed directly as a poetic personification, acting as the subject of the sentence.