I don't know that many English books on Illustrator, but from those I know I would recommend "Real World Illustrator CS5" (there is no CS6 version available). It will teach you the basics and give you an understanding of how it all works. From those basics you can then figure out everything else. Of course you might also read the manual, but Mordy Golding can explain it better ;-)
In order to apply all the features to creative work, you should take a look at "Illustrator WOW".
In addition to what Monika said, you could really learn much by going through the manual and trying out things, and that may cover the whole range. It is a tougher road, but free.
You should know that it is worst in the beginning because some things may be far from obvious, such as where you find the different Tools; after all it is a manual, obviously written by people that know their way round.
And when you get stuck, you can get unstuck here.
... the basic essentials of it ... Illustrator from a book ...
There is also a series by PeachPit Press called "illustrator visual quickstart guide" that may assist you getting to know the essentials so you can then dive deeper with your own initiative once you know the basics. Everyone's learning style and preferences are different so make sure whatever book you choose matches the style you learn best from. Many books can also be previewed in Google books, so you can see how they are setup if you're gonna order online and not review the books first hand in a bookstore.
And as Jacob said you can utilize Adobe's free resources as well to get a great grasp of all the tools and features...
Written documentation and tutorials: