Is aurdiono programing C++

Hello All
I am new in arduino as well as programming. I have couple questions;
The first one is that Is Arduino uses C++ or it has its unique programming language.
The second question is that There are lots of resources about C++, even in a local library, but is there any comprehensive book(or do you recommend any book) that covers all the codes used in arduino programming language with example projects in it (FYI: I have the 'Arduino starter kit' I just want to advance learning more). Please advise.
Thank you.

Yes, it's C++.

There's an Arduino pre-processor that runs on .ino files in an attempt to make it a little easier to use (adds function prototypes and common #includes, etc).

Arduino Programming Reference

The Arduino is programmed in C++. There are many functions that are written specifically for the Arduino family of boards. The Arduino reference covers many of those functions.

The Arduino IDE comes with many many examples. Download and install the IDE and look at File, Examples menu.