This is the 781st most frequent German word.
jörg
"Jörg" is a German male given name, equivalent to "George" in English.
Here, 'Jörg' is the subject of the sentence, representing the person's action of reading.
Jörg liest ein Buch.
Jörg is reading a book.
In this sentence, 'Jörgs' is used in the possessive form, indicating ownership of the dog by Jörg.
Das ist Jörgs Hund.
That is Jörg's dog.
Here, 'mit Jörg' places Jörg as the direct object of the preposition 'with', indicating association or company.