"You read the book."
Translation:Tu librum legis.
The proper Latin sentence for "you read the book" is "tu librum legis". You need a second person singular verb to go with tu; 2nd singular always ends with "s" in the present. You could also use the plural you (you all read the book), which would be "Vos librum legitis". This uses second person plural forms. The 2nd plural ending is always "tis" in the present. Hope this helps.