This is the 16057th most frequent Polish word.
tytułowa
"Title" or "titular" (feminine form).
In this sentence, 'tytułowa' is used as an adjective to describe the main character who is referred to in the title of the book.
Tytułowa postać książki to silna, niezależna kobieta.
The titular character of the book is a strong, independent woman.
Here, 'tytułowego' (the masculine form) modifies 'bohatera' to indicate the hero mentioned in the title of the movie.
Film opowiada o przygodach tytułowego bohatera.
The movie tells the story of the titular hero.
'Tytułowego' describes 'wersu' to signify the verse that shares its text with the title of the song.