This is the 40th most frequent German word.
schon
"Schon" means "already," "yet," or "indeed," depending on context.
In this sentence, "schon" means "already" and emphasizes that the action of reading the book is completed as of now.
Ich habe das Buch schon gelesen.
I have already read the book.
Here, "schon" is used as "even" to indicate that the desire existed from a young age.
Schon als Kind wollte ich immer Lehrer werden.
Even as a child, I always wanted to become a teacher.
In this context, "schon" conveys the meaning of "just" or "simply," expressing satisfaction or acceptance.