German has six words for "the".
There are three genders, and they are not logically assigned. The word for "girl" ("Mädchen") is not feminine. Each has to be memorised (although there are some categories which help).
There are four cases.
I could go on.
if you are from a country in the Anglosphere, this all makes German difficult. The superficial similarities to English mask a grammar that is both flexible and precise but quite complicated.