This is the 317th most frequent Bulgarian word.
неговата
"His" (possessive pronoun).
In this sentence, 'неговата' is used as a possessive pronoun in the feminine form to indicate that the book belongs to 'him'.
Неговата книга е на масата.
His book is on the table.
In this example, 'неговата' again serves as a possessive pronoun referring to 'his,' agreeing with the feminine noun 'идея' (idea).
Аз харесвам неговата идея.
I like his idea.
Here, 'неговата' specifies ownership of the hat, matching the gender of the noun it describes, which is feminine in Bulgarian.