What does this japanese sentence means?

Question:

私に本を上げる???
thx

Answer:

You (or someone) give me a book?

Addition:
There is no word like a and the in Japanese. So I can't see if it's a book or the book from your sentence.

Addition2:
>isn't に is the?

No.

Addition3:
>and why's を is pronounced as o in the sentence?

を is always pronounced as o. There is no other.