This is the 615th most frequent German word.
daniel
In German, "Daniel" is a proper noun, typically used as a male given name, equivalent to "Daniel" in English.
Here, 'Daniel' is used as a proper noun identifying a person engaged in the action of reading.
Daniel liest ein Buch im Garten.
Daniel is reading a book in the garden.
In this sentence, 'Daniel' is used as a person's name to specify someone's identity.
Mein Freund heißt Daniel.
My friend is named Daniel.
Here, 'Daniel' is used as a direct address to get the attention of the person named Daniel.