“Hacking for Dummies” by Kevin Beaver
“The Basics of Hacking and Penetration Testing: Ethical Hacking and Penetration Testing Made Easy 2nd Edition”
by Patrick Engebretson
“Penetration Testing – A Hands-On Introduction to Hacking” by Georgia Weidman
PTSv4 Barebones Edition by eLearnSecurity that you have free access to by becoming a member here.
“The Web Application Hacker’s Handbook: Finding and Exploiting Security Flaws” by Dafydd Stuttard & Marcus Pinto
“Kali Linux Revealed – Mastering the Penetration Testing Distribution” by Raphaël Hertzog, Jim O’Gorman and Mati Aharoni
Not a book but this may help – http://www.pentest-standard.org/index.php/Main_Page
If you look up these titles in Amazon, there are plenty of other titles recommended. Start looking through them to get a feel for what else might be good for you or where you want your career to go.
Hope this helps,
Don