Hi :) C,C++ or Java ?

Hi
I'm Italian and my english is so bad , sorry..

I would ask you what the language is recommended to develop android's app :

Java , C or C++ ? Anothrer doubt but C is used for android app ? mmm ..

There isn't a android native language , right ?
Coult I ask you to suggest me a web site's link where can I see how does android work ?

Sorry for my english , I'm studing english but there are too many word to say same thing
Thanks